Class 12 – Page 6 – Maharashtra Board Solutions

An Astrologer’s Day 12th Question Answer English Chapter 1.1 Maharashtra Board

January 17, 2025January 16, 2025 by Bhagya

Balbharti Yuvakbharati English 12th Digest Chapter 1.1 An Astrologer’s Day Notes, Textbook Exercise Important Questions and Answers.

Class 12 English Chapter 1.1 An Astrologer’s Day Question Answer Maharashtra Board

12th Std English Chapter 1.1 Brainstorming Question Answer

Yuvakbharati English Navneet 12th Digest PDF Free Download Maharashtra Board

Question 1.
Discuss with your partner and complete the table:

Answer:

Your Strengths	Why do you feel so?	Your Dream career
painting and drawing	can visualise, express	commercial artist, cartoonist
…………………….	………………………	………………………….
……………………	………………………	…………………………
…………………..	……………………….	………………………..

Question 2.
The scene in a local market of a village/ town/city is very attractive. People with different occupations sell their wares. Discuss with your partner the variety of activities at the local market.
Answer:

selling flowers, selling grocery
selling garments and cloth
selling imitation jewellery and accessories
selling snacks and fast food
selling steel and earthenwares

Question 3.
In a village/town/city it is quite a common sight to see an astrologer sitting by the roadside with his professional equipment. Discuss with your partner and list the requirements for his trade.
Answer:

parrot, cards, etc.
turban, beard, dhoti
dried leaves with writing on them
cloth with mystic signs to spread his cards
bead necklace, coins, shells, punchang, etc.

Question 4.
There are certain unreasonable beliefs among people living in our society. Certain common events are linked with superstitions. List such events, discuss the superstitions linked with them and the means of their eradication.
Answer:
Events and superstitions linked with them:

A cat crossing your path (something bad will happen)
Walking under a ladder (something unfortunate will happen)
Wearing black clothes for an auspicious function (will bring bad luck to the hosts)
Spilling salt (unlucky for the person)
A black crow cawing outside your window (you will be having guests)

Means of eradication: The only means of eradication is through education. Scientific attitude must be developed in society. Religious heads must counsel and guide their followers. The elders in families must also get rid of old beliefs.

A1.

(i) Given below are some descriptions. Discuss them with your partner and find out one word for each of them.

Question (a)
The scientific study of the universe and the objects in it, including stars, planets, nebulae and galaxies:
Answer:
Astronomy

Question (b)
The study of the movements of the planets, Sun, Moon, and Stars in the belief that these movements can have an influence on people’s lives:
Answer:
Astrology

Question (c)
A prediction of what will happen in the future:
Answer:
Prophecy

Question (d)
Scientific discipline that studies mental states and processes and behaviour in humans and other animals:
Answer:
Psychology

Question (ii)
In the story we are told that the Town Hall Park was a remarkable place in many ways for an astrologer to build his business. List the exceptional qualities of the place from this extract.
Answer:
The exceptional qualities of the place were:

A surging crowd
A variety of trades and occupations, like medicine sellers, sellers of stolen hardware and junk
magicians
auctioneers of cheap cloth
a vociferous vendor of fried groundnuts.

Question (iii)
The astrologer never opened his mouth till the other had spoken for at least ten minutes. Discuss the reasons behind his act.
Answer:
(a) He was good at reading people.
(b) He obtained a lot of information about their lives from their talk.
(c) He could analyse their character and understand their problems.
(d) He could easily frame his statements to their satisfaction.

A2.

Question (i)
The tactics used by the astrologer to earn his wages are:

Answer:

Question (ii)
An astrologer’s appearance helps to create an impression on his clients. Complete the following:
(The answer is given directly and underlined.)
Answer:

The turban on his head
The sacred ash and vermilion on his forehead
dark whiskers covering the face
a sparkle in his eye accompanied by an abnormal gleam

1. Read the following sentences and choose the correct one:

Question (a)
The astrologer says that if Nayak does not leave his village again, he would –
(1) return the money
(2) face danger
(3) go back home and stop looking for the man who tried to kill him
(4) not find the killer.
Answer:
(2) face danger

Question (b)
According to the narrator, the astrologer’s success in his profession is primarily due to –
(1) luck
(2) the bargains he drives
(3) his appearance
(4) his understanding of people.
Answer:
(4) his understanding of people

Question (c)
The story suggests that the astrologer’s comments and observations pleased people by –
(1) promising them success and good fortune
(2) proving, as time passes, to have been true
(3) flattering them or supporting their own views
(4) helping them to learn to solve their own problems.
Answer:
(3) flattering them or supporting their own views

Question (d)
Guru Nayak the astrologer because he wants to –
(1) understand the past
(2) find out who the astrologer is
(3) make some money through a bet
(4) get the answer to a specific question.
Answer:
(4) get the answer to a specific question.

Question (e)
Guru Nayak is looking for the man who tried to kill him –
(1) to take revenge
(2) to get an apology
(3) to demand an explanation
(4) to prove that the man was unsuccessful.
Answer:
(1) to take revenge

Question (f)
The astrologer’s remarks make Guru Nayak feel all of the following except –
(1) relieved
(2) suspicious
(3) impressed
(4) disappointed.
Answer:
(2) suspicious

Question (g)
Reactions of the astrologer’s wife to his news suggest that she –
(1) was unaware of his past
(2) has been worried about his safety
(3) has known him since he was young
(4) is concerned about her future with him.
Answer:
(1) was unaware of his past

Question (iv)
Read the following sentences and find out the True and False sentences. Correct the False sentences:
(a) The astrologer gave a correct prediction to the client about his past that he was stabbed, thrown into a well and left for dead
(b) When the astrologer came to know that the man whom he killed is alive he felt that he was relieved of his guilt.
(c) The astrologer tried to back out of the deal and talked about the client’s past.
(d) The astrologer rescued himself from Guru Nayak’s revenge.
(e) The moral of the story is that we must be responsible about what we have done and should not run away from our mistakes.
Answer:
(a) True.
(b) True: When the astrologer came to know that the man whom he killed is alive he felt that he was relieved of his guilt.
(c) False
Corrected sentence. The astrologer struck a bargain with the client and then talked about the client’s past.
(d) True.
(e) False: The moral of the story is that we must be responsible about what we have done and should not run away from our mistakes.
Corrected sentence: The moral is that we should never believe in superstitions.

Question (v)
The astrologer had changed his appearance and his persona when he arrived in the city. Give specific reasons for this.
Answer:
The astrologer thought that he had killed a man after a quarrel. He was afraid that he would be arrested and jailed for this crime. Hence, to avoid detection he changed his appearance and his persona when he arrived in the city.

Question (vi)
‘The darkness load that was inside the astrologer has disappeared’. Through this sentence, explain the significance of the title ‘An Astrologer’s Day’.
OR
(vii) The astrologer feels relieved that Guru is not dead as it relieves a great burden from him. Critically justify the statement and explain it.
Answer:
The astrologer thought that he had killed a man after a quarrel. Hence he had run away from his village, changed his appearance and his persona when he arrived in the city, and become an astrologer. However, he still felt guilty for what he had done. When he came to know that the man he thought he had killed was actually alive, the dark load inside him disappeared, and it made his day, i.e. he felt relieved and happy. This is the significance of the title ‘An Astrologer’s Day’.

Question (viii)
The astrologer wins/gets the sympathy/ criticism of the reader in the end. Express your opinion with the support of the main story.
Answer:
I think I sympathize with the astrologer. He did not try to intentionally kill Guru Nayak; it had happened in the heat of the moment. Of course, he should not have tried to run away but should have accepted responsibility for his crime. However, he is genuinely sorry for what had happened.

His words ‘a great load is gone from me today. I thought I had the blood of a man on my hands all these years’ indicates this. Hence, I sympathize with him and am happy that he can now live in peace.

Question (ix)
Suggest some steps to eradicate superstitions and other ill practices from our society.
Answer:
To eradicate superstitions and other ill practices from our society the first and most important step is education. Schools and colleges must help their students to develop a scientific attitude and think logically and rationally.

Secondly, as people in India tend to listen to their religious heads, all religious heads should send out clear messages to their followers about the eradication of superstitions. And lastly, the older generation should change their opinions and ideas and get rid of silly superstitious beliefs.

Question (x)
In the story, the astrologer has great listening power. Listening helps in developing good relations with people. Express your opinion.
Answer:
Yes, listening helps in developing good relations with people. When we listen, we indicate to the speaker that we care about him/her and are interested in his/her problems/joys. We show that we are ready to help him/her if necessary. We share his/ her ideas. We also realize how we can deal with people successfully by listening to their views.

(A3)

Question (i)
In the story, the astrologer, Guru Nayak and astrologer’s wife reveal their qualities through words and actions. Pick out from the box the words that describe them and write in the appropriate columns:

Answer:

Astrologer	Guru Nayak	Astrologer’s wife
shrewd	manipulative	caring
clever	gullible	suspicious
smart	quarrelsome	protective
sharp	arrogant	worried
intuitive	aggressive	humanistic
mystical	demanding	rational
cunning	antagonistic
mean	sceptical
over	impetuous
confident

Question 1.
Match the suffixes with the words and make words:

Answer:

Word	Suffix	Noun
auction	able	auctioneer
enchantment	enchantment	enchantment
know	ment	knowledge
prepare	ure	preparation
proceed	tion	procedure
appear (this word is not in the lesson)	ment	appearance
remark	ure	remarkable

Question (iii)
‘An Astrologer’s Day’ has ironic elements where the astrologer pretends to have ‘supernatural knowledge’ that coincidently turns out to be the truth. Find out an example of irony from the extract and write it down:
Find out the examples of irony from the extract and write them down.
Answer:
His eyes sparkled with a sharp abnormal gleam which was really an outcome of a continual searching look for customers, but which his simple clients took to be a prophetic light and felt comforted.
1. He knew no more of what was going to happen to others than he knew what was going to happen to himself the next minute.
2. He was as much a stranger to the stars as were his innocent customers.
3. He said things which pleased and astonished everyone : that was more a matter of study, practice, and shrewd guesswork.

Question (iv)
Find the examples of code-mixing from the extract and write them down.
Answer:
1. ‘cowrie shells’
2. turban

Question (v)
There are some phrases where the word ‘crown’ is used with different shades of meaning. Use the following phrases to complete the sentences meaningfully. One is done for you.
Crowning achievement, to crown the effect, crown of thorns, crowning glory, to crown it all
Answer:
e.g. To crown the effect, he wound a saffron- coloured turban around his head.
(a) The works of Shakespeare are the crowning glory of English drama.
(b) Amitabh has given us awesome movies throughout five decades. But his crowning achievement is his performance in the movie ‘Black’.
(c) In her pursuit of success, Radha has distanced herself from her family. Her fame has become a real crown of thorns.
(d) They threw a wonderful party for me with costumes, games and to crown it all my favourite kind of ice cream.
(e) Medical science has great inventions, but organ transplantation is definitely a crowning achievement for human beings.

(A4)

Question (i)
Use the word given in the brackets and rewrite the sentence:
(a) The power of his eyes was considerably enhanced. (enhancement)
(b) He had a working analysis of mankind’s troubles, (worked)
(c) He knew what was going to happen to himself the next minute. (happening)
(d) If you find my answers satisfactory, will you give me five rupees? (satisfaction)
(e) He shook his head regretfully. (regret)
(f) It was a bewildering crisscross of light rays, (bewildered)
(g) “I should have been dead if some passer-by had not chanced to peep into the well,” exclaimed the other, overwhelmed by enthusiasm. (enthusiastically)
(h) You tried to kill him. (killing)
(i) I will prepare some nice stuff for her. (preparation)
(j) The other groaned on hearing it. (heard)
Answer:
(a) There was considerable enhancement in the power of his eyes.
(b) He had worked out an analysis of mankind’s troubles.
(c) He knew what could be happening to himself the next minute.
(d) If my answers give you satisfaction, will you give me five rupees?
(e) He shook his head with regret.
(f) He was bewildered by the crisscross of light rays.
(g) “I should have been dead if some passer-by had not chanced to peep into the well,” exclaimed the other enthusiastically.
(h) You tried killing him.
(i) I will make a preparation of some nice stuff for her.
(j) The other groaned when he heard it.

(A5)

Question (i)
Prepare a speech on Science and Superstitions.
Answer:
Science and Superstitions
Respected teacher and my dear friends,

I wish you all a very good morning. Today we are celebrating Science day in our school, and on this occasion I, Rohan Kamte, would like to say a few words about Science and Superstitions.

Science and Superstitions are two opposite ends of a pole. Those who have the scientific attitude and believe in science cannot possibly believe in superstitions. After all, what exactly are superstitions? They are only some tales made up by people for some reason or the other. Let me give you an example. Many years ago, in a house in a village, they were having an auspicious function. A lot of food was being cooked.

A cat and her kitten were moving about here and there in the kitchen. Afraid that the cat would be trampled upon or may fall into one of the open fires, the mistress of the house ordered the servant to put the cat and its kitten under a basket, and to do so every time there was a function in the house. This became a ‘superstition’ and in some houses, people actually brought a cat into the house and put it under a basket whenever they had a function!

This is what superstitions are all about. The superstition of bad luck if you walk under a ladder too has its reasons. The ladder could fold up and injure a person walking beneath it, or something could fall on the person’s head.

So friends, I request you: In this age of Science, do not believe in silly superstitions. Keep your minds open. Be rational and logical. Analyse things. Believe something only if it has the backing of Science. Thank you.

(ii) Read the following proverbs. Share you views and expand the ideas.

Question (a)
Actions speak louder than words.
Answer:
Actions speak louder than words

Today a lot of importance is being given to the way we speak and what we speak. But we have to remember that ultimately it is not words but actions that are important. Mahatma Gandhi, the Father of our Nation, did not give any grand speeches. However, by his actions he saw that India gained her freedom. Our soldiers do not give long lectures on patriotism they merely act to defend the country. What would have happened if they had only spoken but not acted?

This very well-known proverb is very apt when it comes to parent-child interaction. It has been seen that children observe the actions of their parents and imitate them not their words. In the animal kingdom too, the actions of the parent are of paramount importance. During elections, politicians make loud speeches but later on do not work. It is because of this behaviour that they lose the trust of the people. Thus, we must act with responsibility, always remembering that people observe our actions and are not swayed by our words.

Question (b)
The face is the index of the mind.
Answer:
[Points: facial expressions and eyes indicate one’s thoughts – this is. non-verbal communication – that is why we smile when happy and frown when sad – however, smart people can hide their feelings so that face does not show them – so one has to be careful while reading faces]

Question (c)
Speech is silver and silence is golden.
Answer:
[Points: we speak – we give others information or reveal our thoughts – others speak, we get information – sometimes we speak hastily and hurt others – create problems – remain silent and think – can find solutions – many leaders speak hastily – create international problems – better to be silent and let one’s actions speak]

Question (d)
Argument is the worst kind of communication.
Answer:
[Points: arguments – people get angry – angry words and raised voices – hurt people – confusion – relationships spoilt – instead talk softly and allow others to talk – accept that others can think in a different way – ‘a man convinced against his will is of the same opinion still’]

Question (e)
Attitudes are the real figures of speech.
Answer:
[Points: quote by Edwin H Friedman – in communication, more than the verbal message, the non-verbal message important – your attitude and behaviour have more impact than your words – for example, if you say ‘sorry’ in a harsh tone without any apology on your face – the word has no meaning – hence body language and attitude are very important)

Question (f)
The wise man has long ears and a short tongue
Answer:
[Points: better to listen than to speak – wise people listen more and speak only when they have something important to say – speech is silver and silerwe is golden – in any situation it is better to remain silent and evaluate situation – empty vessels make the most noise]

(A6)

Question (i)
Bill Naughton has written a collection of wonderful stories which you can read in his book ‘The Goal Keeper’s Revenge and Other Stories’. Read all the stories and discuss their themes with your partner.

Question (ii)
Read R.K. Narayan’s humorous collections of short stories and novels. Here are some titles you can read.
(a) ‘Under The Banyan Tree’
(b) ‘The Doctor’s Word’
(c) ‘LawleyRoad’
(d) ‘A Horse and Two Goats’
(e) ‘Gateman’s Gift’

(A7)

Question 1.
Surf the internet and find out the career opportunities in Astronomy.

Yuvakbharati English 12th Digest Chapter 1.1 An Astrologer’s Day Additional Important Questions and Answers

Read the extract and complete the activities given below:

Global Understanding:

Question 1.
List the fancy names the vendor of fried groundnuts gave his wares.
Answer:
The fancy names the vendor of fried groundnuts gave his wares are:

‘Bombay Ice Cream’
‘Delhi Almond’
‘Raja’s Delicacy’, etc.

Question 2.
Complete the following:
(The answer is given directly and underlined.)
Answer:
If the astrologer had stayed in the village, he would have carried on the work of his forefathers-namely, tilling the land, living, marrying and growing old in his cornfield and ancestral home.

Question 3.
The Town Hall Park was a remarkable place in many ways for an astrologer to build his business. List the exceptional qualities of the place from the extract.
Answer:
The exceptional qualities of the place were:

lack of municipal lighting
flare from the groundnut heap
hissing gaslights, some with naked flares, and cycle lamps
bewildering criss-cross of light rays and moving shadows

Question 4.
Complete the following:
(The answers are given directly and underlined.)
The signal for the astrologer to leave was when the nuts vendor blew out his flare and rose to go home.
The astrologer spoke only when his client had spoken for at least ten minutes.

Question 5.
Rearrange the following sentences in the order of their occurrence in the extract:

“I will speak to you tomorrow.”
“Oh, stop that,” the other said.
“There is a woman ”
“Or will you give me eight annas?”

Answer:

“Oh, stop that,” the other said.
“Or will you give me eight annas?”
“I will speak to you tomorrow.”
“There is a woman ………..”

Complex Factual:

Question 1.
Complete the following:
(The answer is given directly and underlined.) The tactics used by the astrologer to earn his wages are:
Answer:

Question 2.
Describe how the astrologer had left the village.
Answer:
The astrologer had left the village without any previous thought or plan. He had left home without telling anyone. He did not rest till he left behind his village a couple of miles.

Question 3.
The astrologer could understand the problem in five minutes. Give reasons from the extract.
Answer:
The astrologer had a working analysis of mankind’s troubles like marriage, money and the tangle of human ties. Long practice had sharpened the way he perceived things, and thus he could understand the problem in five minutes.

Question 4.
Complete the following :
(The answer is given directly and underlined.)
Answer:

Question 5.
Complete the web:
(The answers are given directly and underlined.)
Answer:

Question 6.
Complete the following with what had happened to Guru Nayak’s enemy, according to the astrologer. According to the astrologer ………….. .
Answer:
According to the astrologer, Guru Nayak’s enemy had died. He had been crushed by a lorry.

Question 7.
Describe the load on the astrologer’s mind.
Answer:
The astrologer thought that he had killed a man after a quarrel. He felt intensely guilty about this, and had run away from his village. This feeling of guilt was the load on his mind.

Question 8.
Was the astrologer’s wife happy with his day’s earnings? What did she plan to do with it?
Answer:
Yes, the astrologer’s wife was overjoyed with his day’s earnings. She planned to buy some jaggery and coconut and make some sweets for their daughter.

Inference/Interpretation/Analysis:

Question 1.
The presence of the groundnut vendor is beneficial to the astrologer. Justify.
Answer:
The vendor of fried groundnuts gave his wares fancy names like ‘Bombay Ice Cream’, ‘Delhi Almond’, ‘Raja’s Delicacy’ and so on. People were amused and attracted by this and flocked to him to buy groundnuts. As the astrologer was seated right next to him, the groundnut vendor’s customers dallied near the astrologer and were probably tempted to consult him.

Question 2.
Pick out the lines that tell you that the astrologer did not have any real knowledge of astrology.
Answer:

He had not in the least intended to be an astrologer when he began life.
He knew no more of what was going to happen to others than he knew what was going to happen to himself the next minute.
He was as much a stranger to the stars as were his innocent customers.
It was a bewildering crisscross of light rays and moving shadows. This suited the astrologer very well.

Question 3.
The astrologer could tell the person/client about his life. Describe the method he used.
Answer:
The astrologer would listen to his client talk for about ten minutes. He would thus get all the information about his life from him, and then cleverly pose questions which made it appear that he actually knew about the person’s life.

Question 4.
‘Our friend felt piqued.’ Name the friend and give reasons for him feeling ‘piqued’.
Answer:
‘Our friend’ is the astrologer. He felt piqued because the man cut short his words rudely and told him to tell him something worthwhile. The astrologer was used to people listening eagerly and respectfully to whatever he had to say, and the behaviour of the man showed that he did not value the usual smooth talk. That is why the astrologer felt piqued.

Question 5.
Complete the following:
(The answers are given directly and underlined.)
Answer:
1. The man was left for dead because he had been pushed into a well in a field. Nobody normally looked into the well, and he would have died had there not been a passer-by who chanced to peep into the well.
2. The man looked gratified because his enemy had met his death by being crushed under a lorry. Guru Nayak felt that the man deserved such a terrible fate for what he had done to him.

Personal Response:

Question 1.
Do you like to hear predictions about your future? Give reasons.
Answer:
No, I do not like to hear predictions about my future. I do not believe that any person can foretell what is going to happen in someone’s life. Astrology is just a way of making money from gullible people. I believe that one must work hard and be a good human being if one wants to be successful in life.

Question 2.
Do you think that astrology is an art and can be studied? Discuss.
Answer:
Yes, astrology is an art. There are various methods of predicting the future, like palm-reading, reading the pulse, reading the horoscope, etc. These methods can be studied, or the knowledge can be inherited from one’s ancestors. However, the astrologer must have intuition and talent for this art.

Question 3.
Explain with examples your reactions when someone challenges you.
Answer:
If the challenge is worthwhile, I take it up. For example, my friend Rohan challenged me to a bicycle race to the top of a nearby hill. I took it up as it was interesting, and I knew I could do it.

However, when my friend Soham challenged me to jump from the first floor of our building, I refused the challenge, as I knew it was dangerous and I was likely to break some bones. Though Soham scoffed at me, and said that he had already done it, I did not let his ridicule bother me.

Language Study:

Question 1.
The power of his eyes was considerably enhanced by their position.
(Rewrite beginning ‘The position …………’)
Answer:
The position of his eyes considerably enhanced their power.

Question 2.
This colour scheme never failed.
(Rewrite as an affirmative sentence.)
Answer:
This colour scheme was always successful.

Question 3.
He had left his village without any previous thought or plan. (Rewrite using neither … nor …’)
Answer:
He had left his village with neither any previous thought nor plan.

Question 4.
One or two had hissing gaslights. (Identify the part of speech of the underlined word.)
Answer:
hissing – adjective (present participle used as an adjective)

Question 5.
He never opened his mouth till the other had spoken for at least ten minutes.
(Rewrite using ‘only’.)
Answer:
He opened his mouth only after the other had spoken for at least ten minutes.

Question 6.
He looked up and saw a man standing before him. (Rewrite as a simple sentence.)
Answer:
Looking up, he saw a man standing before him.

Question 7.
If I prove you are bluffing, you must return that anna to me with interest. (Pick out the clauses and state their type.)
Answer:
you must return that anna to me with interest-main clause
If I prove you are bluffing-adverb clause of condition

Question 8.
“Tell me something worthwhile.” (Identify the type of sentence.)
Answer:
Imperative sentence.

Question 9.
Never travel southward again, and you will live to be a hundred. (Rewrite using ‘only if)
Answer:
You will live to be a hundred only if you never travel southward again.

Question 10.
He flung the coins at her and said “Count them. One man gave all that.” (Rewrite in reported speech.)
Answer:
He flung the coins at her and instructed her to count them. He added that one man had given all of it.

Question 11.
I will prepare some nice stuff for her. (Rewrite using the past perfect tense of the verb.)
Answer:
I had prepared some nice stuff for her.

Vocabulary:

Question 1.
Match the suffixes with the words and make words:
Answer:

Word	Suffix	Noun
innocent	able	innocence
reason	ledge	reasonable

Question 2.
Pick out two words from the extract that indicate sound.
Answer:
crackled, hissing

Question 3.
Guess the meaning of ‘pies’
Answer:
pies – is the plural form of pie which is a former bronze coin of India, the 12th part of an anna.

Question 4.
Find an example of code mixing from the extract and write it down.
Answer:
pies

Question 5.
Find out the examples of irony from the extract and write them down.
Answer:
1. When he told the person before him, gazing at his palm, “In many ways you are not getting the fullest results for your efforts,” nine out of ten were disposed to agree with him.
2. “Most of your troubles are due to your nature. How can you be otherwise with Saturn where he is? You have an impetuous nature and a rough exterior.” This endeared him to their hearts immediately, for even the mildest of us loves to think that he has a forbidding exterior.

Question 6.
Guess the meaning of the words:

tilting
bluffing
glimpse

Answer:

tilting – to move into a sloping position.
bluffing – deceiving, lying
glimpse – to see someone or something for a very short time

Question 7.
Find examples of code mixing from the extract and write them down.
Answer:

anna
rupee
cheroot
jutka

Question 8.
Guess the meaning of the words:

passer-by
peep
overwhelmed
groaned

Answer:

passer-by – a person who happens to be going past something or someone, especially on foot.
peep – to peer into something cautiously
overwhelmed – overcome
groaned – made a low sound of distress.

Question 9.
Find examples of code mixing from the extract and write them down.
Answer:
1. annas
2. pyol

Question 10.
Find from the extract the antonyms of the following words:

light
noise
few
dead

Answer:

light × darkness
noise × silence
few × many
dead × alive

Non-Textual Grammar:

1. Do as directed:

Question 1.
A stone struck the man on the head.
(Rewrite using the passive voice.)
Answer:
The man was struck on the head by a stone.

Question 2.
You will not recover. Refrain from smoking.
(Rewrite using ‘unless’.)
Answer:
You will not recover unless you refrain from smoking.

Question 3.
He is certainly taller than his brother.
(Rewrite in the positive degree.)
Answer:
His brother is certainly not as tall as he is.

Spot the error in the following sentences:

Question 1.
His mouth watered when he saw a bouquet of grapes.
Answer:
His mouth watered when he saw a bunch of grapes.

Question 2.
They left their luggages at the railway station.
Answer:
They left their luggage at the railway station.

12th Std English Questions And Answers:

Into the Wild 12th Question Answer English Chapter 1.6 Maharashtra Board

January 17, 2025January 16, 2025 by Bhagya

Balbharti Yuvakbharati English 12th Digest Chapter 1.6 Into the Wild Notes, Textbook Exercise Important Questions and Answers.

Class 12 English Chapter 1.6 Into the Wild Question Answer Maharashtra Board

12th Std English Chapter 1.6 Brainstorming Question Answer

Yuvakbharati English Navneet 12th Digest PDF Free Download Maharashtra Board

Question 1.
Narrate in your class any of the incidents of your life when you were extremely terrified or awestruck.
Answer:
(Points: alone on a lonely road – lost somewhere – seeing a beautiful sunset – seeing beautiful mountains, etc.)

Question 2.
Complete the given table regarding the factors/situations/reasons – why you sometimes get scared and the factors that add to it. Give possible solutions:
Answer:

Reasons	Factors which add to it	Solutions
1. While discussing about strange creatures	At midnight/ In the absence of parents	Avoid such discussions/ stories as they are baseless
2. If I get lost somewhere and cannot find my way home	If I am alone/ if it is at night/ if the place is lonely	Find out the way/route in detail before hand/Try not to go out at night alone.
3. Just before the exams.	If I am not prepared for them/ if I have not studied	Have a regular timetable for studies/make sure that I find ways to prepare subjects that I find difficult.

Question 3.
Given below are various activities which you can pursue as your hobby, passion, or profession. Complete the table accordingly:

Answer:

Activities	Hobby	Passion	Profession	Reason/Challenge/Both
Painting	✓	✓	✓	(R) I can express myself well through the strokes of brush
Traveling	✓	✓	✓	(R) In tourism, there is great demand for professional tourist guides.
Wildlife photography	✓	✓		(C) In the age of computers limited professional scope
Conserving environment		✓	✓	(C) In a world which is careless, a tremendous challenge
Bird Watching	✓	✓		(R) Extremely interesting and rewarding; professional opportunities few

Question 4.
Match the following ‘Wildlife Sanctuaries’ with their locations:

Answer:

Wildlife Sanctuary	Location
1. Bandipur National Park	(c) Karnataka
2. Kaziranga National Park	(d) Assam
3. Jim Corbett National Park	(a) Uttarakhand
4. Ranthambore National Park	(e) Rajasthan
5. Kanha National Park	(b) Madhya Pradesh

(A1)

Question (i)
In pairs, discuss the professions and challenges one can take happily if one is really passionate about the job.
(Points – professions: photography, environmental conservation, writing, reporting, music, choreography, etc. challenges – low salary, difficulties with organizations, uncooperative colleagues, severe competition, etc.

Question (ii)
In groups, organize a role play activity associated with ‘Wildlife Expert’/‘Wildlife Photographer’/ ‘Wildlife Conservator’, explaining the differences and similarities involved in their profession.
(Students can find out the details of each profession from the internet and organize a role play.)

(A2)

Question (ii)
Correct the false statements:
1. Earlier Shaaz was in the field of finance.
2. The writer saw the fight between the two leopards.
3. The photograph of the old leopard made Shaaz famous.
4. Saya is a black panther.
Answer:
False statements:
2. The writer saw the fight between the two leopards.
3. The photograph of the old leopard made Shaaz famous.
Corrected statements:
2. The writer did not see the fight between the two leopards.
3. The photograph of the young leopard made Shaaz famous.

Question (iii)
Complete the given web:

Answer:

Question (iv)
Complete the following:

Answer:

Question (v)
Complete the flow chart stating the reactions of the petrified Langurs due to the presence of the Leopard.

Answer:

Question (vi)
Complete the web, describing each step taken by the writer as a solitary traveller while moving in the jungle with great precaution:

Answer:

Question (vii)
Complete the table explaining the qualities that you would like to imbibe from Nature within yourself and provide the reasons for the same:
Answer:

From	Quality	Reasons
Trees	Patience	Trees patiently bear up with seasons like winter and autumn, and the attacks on them by animals, birds and humans, and wait for spring, to bloom again.
Streams	Perseverance	Streams can even wear down rocks with their perseverance.

(A3)

Question (i)
Choose the appropriate phrase/ expression from the extract given in the brackets: (time and again, to one’s heart’s content, in a jiffy)
(a) I was on a diet for some days but today I am going to eat ……………… .
(b) Every mother scolds her children …………… for the overuse of the mobile phone.
(c) All their educational problems were sorted out ………….. because of the funds given by an NGO.
(d) Raj ran at a ……………… to catch the train.
Answer:
I was on a diet for some days but today I am going to eat to my heart’s content.
Every mother scolds her children time and again for the overuse of the mobile phone.
All their educational problems were sorted out in a jiffy because of the funds given by an NGO.
Raj ran at a frantic speed to catch the train.

(A4)

(i) Begin the following sentences with the words given in the brackets:

Question (a)
I can guide visitors. (Visitors….)
Answer:
Visitors can be guided by me.

Question (b)
Animals are paying me back. (I……..)
Answer:
I am being paid back by animals.

Question (c)
Madegowda is employed by The Bison.
(The Bison )
Answer:
The Bison employs Madegowda.

Question (d)
Older leopards like Pardus carry away livestock from villages. (Livestock….)
Answer:
Livestock are carried away from villages by older leopards like Pardus.

Question (e)
I have lost almost 80 per cent of a season’s yield of sugarcane. (Almost 80 per cent.)
Answer:
Almost 80 per cent of a season’s yield of sugarcane has been lost by me.

Question (f)
Tracking an animal also teaches you life lessons. (Life lessons)
Answer:
Life lessons are also taught by tracking an animal.

Question (g)
Many things have been taught to me by the forests. (The forests)
Answer:
The forests have taught me many things.

Question (h)
Resentment among locals towards the animals is created by this. (This)
Answer:
This creates resentment among locals towards the animals.

(ii) Rewrite the sentences by using ‘not only…… but also’:

Question (i)
Rewrite the sentences by using ‘not only….but also’:
1. The petrified Langurs speeded to the trees near and far and secured their places on the treetops.
2. Umbarzara is the haven for Tigers, Leopards and Sloth Bears.
3. I crossed the cement pillar and stones stacked by the Forest Development Corporation.
Answer:
1. The petrified Langurs not only speeded to the trees near and far but also secured their places on the treetops.
2. Umbarzara is the haven not only for Tigers but also for Leopards and Sloth Bears.
3. I crossed not only the cement pillar but also the stones stacked by the Forest Development Corporation.

(A5)

Question (i)
Your college has decided to celebrate the World Environment Day. Mr. Kiran Purandare has been invited as the ‘Chief Guest’ for the event. Imagine you are the Secretary of the ‘Nature Club’ of your college and you have to conduct an interview of Mr. Kiran Purandare. Frame 8/10 questions for the same.
Answer:
Questions to interview Mr Kiran Purandare

Good morning, Sir. On behalf of the Nature Club of our college, I congratulate you on your achievements. We also loved your book ‘Sakha Nagzira’. I would like to ask you a few questions. May I? Thank you.

Please tell us something about the ‘Environmental Studies’ Course that you studied’.
Are there any such courses in India, especially in Maharashtra?
How did you get interested in the conservation of the environment?
Do you think that we, in Maharashtra, are doing enough to look after our environment?
How can we get permission to spend time inside sanctuaries?
You were mostly a solitary traveller inside the forest. What was the reason for this?
Are there any excursions/expeditions in which you are going to participate, in the near future?
How can we help you in your work?
Any tips/message for our Nature Club?

Thank you, sir, for answering our questions so frankly. We wish you all the best in your future endeavours.

Question (ii)
Imagine you have visited the jungles of Nagarhole. Write a report, to be published in your college magazine/in a local newspaper.
Answer:
A Week in a Jungle

Mysuru, 13 May: Four of us from N.S. College, Mysuru, spent a week at Nagarhole National Park (Rajiv Gandhi National Park), located in Kodagu District.

It was an exhilarating and educative week. The park is filled with waterfalls, hills, valleys, streams and forests. It is famous for its rich population of animals and birds. The Bengal Tiger, Indian Leopard, Sloth Bear, Striped Hyena, etc. are the predators that can be spotted in the park. Herbivores like Elephants, Chital, Sambar Deer and Barking Deer are also spotted around the national park.

As it was the month of May, and the water holes were drying up, plenty of animals visited the lake, and we had a grand time observing their habits from the machaan which was built for tourists. We were particularly careful not to disturb the environment by talking loudly or playing music. Hence, the animals were at their natural best. We were thrilled to see a pair of Bengal Tigers and a Leopard.

It was wonderful to see these majestic animals from such a close distance. It is truly an unforgettable experience. We could not see the Sloth Bear, but there were plenty of elephants and deer. After an experience like this one, all four of us have decided to visit various sanctuaries and take an avid interest in the wildlife of India.
– Shantanu Pratap.

Question (iii)
Shaaz has contributed towards conserving the wild animals and their habitat. Your college has decided to spread the message in society and arrange a rally. Prepare an ‘Appeal’ to ensure maximum participation informing about the day, date and other relevant details.
Answer:
Come One Come All!
Come With Friends And Family!

We need your help to save our planet!
Every species is essential for the survival of the planet.
Hence, we need to protect and conserve wild animals and their habitat.
You are the One With A Voice
Protect The Ones Without A Voice

Participate in our rally.
N.S. College Grounds To Forest Office
Date: 12 November Time: 9 a.m.
Save Animals-They Will Save You!

Question (iv)
Nature is a great teacher and a guide. Complete the mind map as instructed as per the titled concept:

Answer:

(A6)

Question (i)
Surf the net and obtain more information about the conservation work done by Shaaz. Prepare posters to inspire others and display them on your college notice board.

Question (ii)
Find out the information about the I qualification and eligibility required in the professions related to wildlife such as …………

Forest officer/Ranger
Wildlife photographer
Environmentalist
Geologist
Tour Manager

Yuvakbharati English 12th Digest Chapter 1.6 Into the Wild Additional Important Questions and Answers

Read the extract and complete the activities given below:

Global Understanding:

Question 1.
Pick out the sentences that are false and write them correctly:
1. The narrator had made notes of the langurs in the region.
2. One has to be really alert while walking in the jungle.
3. The leopard was petrified.
4. There was a lot of noise in the jungle.
Answer:
False sentences:
1. The narrator had made notes of the langurs in the region.
3. The leopard was petrified.
Correct sentences:
1. The narrator had made notes of the birds in the region.
2. The langurs were petrified.

Question 2.
Complete the following:
Answer:
1. Shaaz named the leopards:
(a) Saya
(b) Scarface
(c) Pardus
2. The visitors are welcomed because they can volunteer to teach a skills training class of their choice. This enables locals to find employment either at the numerous wildlife resorts in the region or in a city.

Question 3.
Correct the false statements:
1. BCRTI was founded out of the genuine urge to conserve the habitat of the wild life.
2. Shaaz failed to utilize the finance incurred out of tourism.
3. According to the local agriculturist seeing is more essential than listening.
4. There was no specific buffer zone around Nagarhole.
Answer:
False statements:
2. Shaaz failed to utilize the finance incurred out of tourism.
3. According to the local agriculturist seeing is more essential than listening.
Corrected statements :
2. Shaaz put the finance incurred out of tourism to good use.
3. According to the local agriculturist listening is more essential than seeing.

Complex Factual:

Question 1.
Pick out from the extract four sentences that show that the writer was frightened.
Answer:

The evening breeze flew through my wet curled hair.
My stomach was aching.
My legs were trembling.
The shaking of limbs had lessened a bit.

Question 2.
Describe the meaning of the acronym BCRTI and explain its benefits to the local people.
Answer:
The BCRTI is ‘Buffer Conflict Resolution Trust of India’. It’s an agency that educates villagers who live on the fringe of the forest on the importance of conservation. Under the BCRTI umbrella, Shaaz provides locals with vocational training, with the aim of educating them on the merits of conservation and to help them benefit from tourist currency. The visitors at the resort are welcome to volunteer to teach a skills training class of their choice. The acquired skills enable locals to find employment.

Inference/Interpretation/Analysis:

Question 1.
Explain: I was alone here like a fox:
Answer:
Foxes are solitary creatures. They move around and hunt alone. In the same way, the narrator was alone; he had come to the forest alone to do his research, and now he was going back to the village all alone. Hence, he compares himself to a fox.

Question 2.
Give the meaning of the word ‘hide’ in the context and give reasons for its usage here.
Answer:
A hide is a camouflaged shelter used to get a close view of wildlife. It is a place built to look like its surrounding. The writer was observing birds and noting their behaviour. If he was visible, the birds would not come near him or act in a natural manner. Hence, he had to build a hide, conceal himself in it and then observe birds unnoticed.

Question 3.
Give reasons:
Answer:
1. After meeting Raju, the writer and Raju both felt relaxed because now there were two of them-four eyes and four hands with a stick-to find their way out of the jungle and to battle predators.
2. The time was dreadful because it was evening and the sun was setting. Being alone in the jungle at night time with predators all around was dreadful.

Question 4.
What is called ‘silver lining’ of the trail by the writer? Why?
Answer:
The writer had lost his way in the jungle and was desperate to find a village and civilization. Then he found a bright red soil trail with the marks of a bicycle wheel on it. These marks showed that there was a village nearby. To the frightened and desperate writer, this was like a ‘silver lining’.

Question 5.
The writer said, “There still exists a jungle where we can get lost, isn’t this our good luck?” What does he mean by this?
Answer:
Human beings have tried to take over all the natural areas of the world. We have encroached on jungles and forests, and there are human inhabitations within the jungles too. To find a jungle where there is no sign of human life, and one can still get lost, shows that there are some areas untouched by humans and left to nature. That is what the writer called ‘our good luck’.

Question 6.
Describe Shaaz’s meetings with Scarface.
Answer:
One day, at sunset, Shaaz and his companions went round a blind turn and saw an old leopard, well past his prime. Close to him was another very young, good-looking male leopard who was soon to come into his prime. It was like looking at the past and the present. It was clear that there was going to be a fight. However, they had to leave as it was sunset.

The next day, when Shaaz went back to the spot, sitting on the high rock was Scarface, blood dripping from a gash across his face. He sat there like he was the king of the jungle, and Shaaz knew that he had taken over from the old leopard, and it was a new journey for both of them.

Question 7.
Find: The Bison is
Answer:
The Bison is an eco-friendly wildlife camp in South India. It offers some great opportunities for youngsters to learn about the area, people, the man-animal conflict, eco-tourism and hotel management.

Personal Response:

Question 1.
Describe a safari you have been on or a trip through a forest. Narrate your experience in brief.
Answer:
I have gone to the Periyar National Park in Kerala. It is in the Western Ghats. This wildlife sanctuary is home to tigers and elephants. There are also deer, leopards and Indian bison. I have also been on a boat ride in the Periyar Lake. It was a wonderful experience to see tigers drinking at the watering holes. I really enjoyed the experience and will repeat it as soon as I can.

Question 2.
Have you ever been lost/lost your way? Narrate the experience.
Answer:
Yes, once when I was in Panchgani with my family I got lost. I decided to go for a walk alone. I set out without finding out the name of the road on which our hotel was situated. As I was walking, it suddenly began to rain heavily, and got quite dark. When I looked around I found that I was in a sort of a jungle. I was terrified; then I met a villager, but he could not help me. I did not even have my cellphone with me. I was in tears when all at once I saw my hotel. I had walked round in circles! I was very relieved. It was indeed a frightening experience.

Question 3.
How do you relax at the end of a tiring day? Give a brief description.
Answer:
At the end of a tiring day, I pick up a nice book or watch a good film on TV or Netflix. This relaxes me completely. If I go to sleep j directly, I am too tired and do not get good sleep. But if I spend half an hour or so unwinding, I really feel relaxed and sleepy.

Question 4.
Would you like to meet wild animals face to face? Give reasons to support your answer.
Answer:
No, I would not. I like to see wild animals only on TV. I feel that we should not intrude into their territory, and leave them to live in peace. Besides, they are wild and not tame, and one never knows how they may behave. I have read about a lot of people being killed by wild animals.

Language Study:

Question 1.
The surroundings were reminding me.
(Rewrite, beginning the sentence with ‘I…)
Answer:
I was being reminded by the surroundings.

Question 2.
I had apparently entered in the sanctum sanctorum of a miracle called leopard.
(Pick out the finite verb/s and state the tense.)
Answer:
had entered – past perfect tense.

Question 3.
Raju was amazed at my solitary visits to Umbarzara.
(Rewrite beginning ‘My solitary’)
Answer:
My solitary visits to Umbarzara amazed Raju.

Question 3.
Then we both resumed our walking tour, (Identify the part of speech of the underlined word.)
Answer:
walking-present participle acting as an adjective.

Question 4.
I found a bright red soil trail. (Rewrite beginning with‘A ’.)
Answer:
A bright red soil trail was found by me.

Question 5.
I had no other way to climb the hillock before me. (Rewrite as an affirmative sentence.)
Answer:
This was the only way I had to climb the hillock before me.

Question 6.
I climbed one more hillock and tried to locate signs of human civilization. (Rewrite beginning ‘Climbing’.)
Answer:
Climbing one more hillock, I tried to locate signs of human civilization.

Question 7.
The behaviour of the first black panther is being documented. (They….)
Answer:
They are documenting the behaviour of the first black panther.

Question 8.
All the research on the animal has been done through camera traps. (They….)
Answer:
They have done all the research on the animal through camera traps.

Question 9.
Shaaz recalls the incident with great clarity.
(Rewrite the sentence replacing the underlined expression with a single word.)
Answer:
Shaaz recalls the incident clearly.

Question 10.
Unfortunately, the sun was setting and we had to leave. (Rewrite using ‘because’.)
Answer:
Unfortunately, we had to leave because the sun was setting.

Question 11.
Use the word ‘guide’ as a noun and a verb in two separate sentences:
Answer:
1. We can guide children to behave well. {verb)
2. I hired a local guide to show me the sights of the palace, {noun)

Question 12.
The black panther has taught me patience. (Rewrite using the adjective form of the underlined word.)
Answer:
The black panther has taught me to be patient.

Question 13.
Listening is a sense far more important than sight. (Rewrite using ‘as…as…’)
Answer:
Sight is a sense not as important as listening.

Vocabulary:

Question 1.
Guess the meaning of the following words :

upheaval
predator
hovering
antelope

Answer:

upheaval – uproar; disturbance.
predator – an animal that preys on other animals.
hovering – fluttering in the air.
antelope – deer-like animal with hollow horns.

Question 2.
Give the meaning of the phrase ‘to stay put’ and use it in your own sentence.
Answer:
to stay put:
Meaning: remain somewhere without moving.
Sentence: My mother told me to stay put near the entrance when she went to buy the train ticket.

Question 3.
Write two adjectives from the extract used for the leopard.
Answer:
mighty, elusive.

Question 4.
Choose the correct option for: spooked –
(a) frightened
(b) happy
(c) angry
Answer:
frightened

Question 5.
Find the contextual meaning of‘stacked’:
Answer:
stacked – piled one on top of the other

Question 6.
Guess the meaning of ‘in a jiffy’:
Answer:
in a jiffy – in a moment; very soon

Question 7.
Make sentences of your own using the words:
1. slumped
2. stumbled
Answer:
1. slumped: I was so tired after the trek that I slumped onto my bed and fell I asleep immediately.
2. stumbled: I did not see the stone in the middle of the road and stumbled over it.

Question 8.
Guess the meaning of:
1. ‘felines’
2. chronicler
Answer:
1. felines: belonging to the cat family,
2. chronicler: a person who records something.

Question 9.
Pick out two pairs of antonyms from the : extract:
Answer:
1. old × young
2. past × present

Question 10.
Write the noun forms of:

famous
enviable
collect
including

Answer:

famous – fame
enviable – envy
collect – collection
including – inclusion

Question 11.
Write the adjective forms of the following:

incursion
territory
resentment
occasion
employment
region

Answer:

incursion – incursive
territory – territorial
resentment – resentful
occasion – occasional
employment – employable
region – regional ?

Question 12.
Choose the correct simple past tense forms of the following from the brackets:

teach – (teached, teaching, taught)
lose – (loser, lost, loose)
put – (put, putted, putting)
learn – (lean, learnt, learns)

Answer:

teach – taught
lose – lost
put – put
learn – learnt.

Non Textual Grammar:

Do as directed:

Question 1.
He had won a prize in the drawing competition. (Rewrite using the future perfect tense of the verb.)
Answer:
He will have won a prize in the drawing competition.

Question 2.
How could I call him a liar? (Rewrite as an assertive sentence.)
Answer:
I could not call him a liar.

Question 3.
All other things are unimportant. (Add a question tag.)
Answer:
All other things are unimportant, aren’t they ?

Spot the error in the following sentences and rewrite them correctly:

Question 1.
Unless you do not listen to his advice, I am not going to help you.
Answer:
Unless you listen to his advice, I am not going to help you./If you do not listen to his ? advice, I am not going to help you.

Question 2.
Hardly had I reached the airport where I heard about the change in plans.
Answer:
Hardly had I reached the airport when I heard about the change in plans.

12th Std English Questions And Answers:

On Saying “Please” 12th Question Answer English Chapter 1.2 Maharashtra Board

January 17, 2025January 16, 2025 by Bhagya

Balbharti Yuvakbharati English 12th Digest Chapter 1.2 On Saying “Please” Notes, Textbook Exercise Important Questions and Answers.

Class 12 English Chapter 1.2 On Saying “Please” Question Answer Maharashtra Board

12th Std English Chapter 1.2 Brainstorming Question Answer

Yuvakbharati English Navneet 12th Digest PDF Free Download Maharashtra Board

Question 1.
List the words of courtesy that we use in our daily life. Discuss them with your partner and explain the purpose of using each.

Answer:

Question 2.
Listed below are a few character traits of people. Some are positive traits, while others are not. Tick [✓] the ones you feel are desirable.

Answer:

Question 3.
Etiquette and manners are very important for a person to live in the society. Read the following and put them in proper columns:

To receive phone calls while you are in a lecture or class.
To knock before you enter your Principal’s office.
To thank the person who offers you tea or coffee.
To be polite and courteous to others.
To leave the classroom without the teacher’s permission.
To occupy the seats reserved for ladies or physically challenged or elderly people on a bus or a train.

Answer:

Appropriate	Inappropriate
1. To knock before you enter your Principal’s office.	1. To receive phone calls while you are in a lecture or class.
2. To thank the person who offers you tea or coffee.	2. To leave the classroom without the teacher’s permission.
3. To be polite and courteous to others.	3. To occupy the seats reserved for ladies or physically challenged or elderly people on a bus or a train.

(A1)

Question (i)
Form groups and explain the following words with examples:
Answer:
1. Humility: being free from pride and arrogance – greatest example our former President Dr. A.P.J. Abdul Kalam – remember that ‘pride comes before a fall’ – always realize that there are people better than you are – Socrates said ‘One thing only I know, and that is that I know nothing. ’
2. Self-esteem: self-respect; confidence in one’s own worth or abilities – accept oneself as one is – everyone is different and unique – highly positive quality – leads to achievements, success, healthy relationships – can be developed with a little effort.
3. Gratitude: thankfulness for something that you have got – ready to show appreciation for something – towards the Almighty, towards those who have helped you – strengthens relationships with others – creates positivity.
4. Courtesy: means good manners and polite behavior – means being kind and compassionate towards others – should be real, not artificial – creates good impression – one will be liked by all – human quality not present in animals.
5. Generosity: kindness; big-heartedness – the act of being kind, selfless and giving towards others – very positive trait – influences others – when one is generous, one feels good – many religions consider this a great virtue – encourage charity.
6. Sympathy: feelings of pity and sorrow for someone else’s misfortune – leads to stronger relationships – offering condolences when someone dies – helps us to bond with others-makes the other person’s distress less – beautiful emotion – should be developed.
7. Empathy: the ability to understand and share the feelings of another – putting yourself in the shoes of the other person – different from kindness or pity – listen when people talk – see things from the other person’s point of view – makes one a very humane person.

Question (ii)
Have a Group Discussion on the topic ‘The need of soft skills at the workplace’. Use the following points:
Answer:
(a) Written and verbal communication (writing notes, letters, memos, reports, instructions, speeches, presentations, etc.)
(b) Ways of interacting with others (showing courtesy, sympathy, cooperation, empathy, strictness, gratitude, humility, team work, etc.)
(c) Creative abilities (preparing reports, presentations, letters, etc.)
(d) Emotional intelligence (showing understanding, compassion, empathy, team work, motivation, self-awareness, etc.)

(A2)

Question (i)
Read the text and state whether the following statements are True or False. Correct the False statements.
(a) Bitter problems in day-to-day life can be solved by sweet words.
(b) Great wars could have been avoided by a little courtesy.
(c) Observance of etiquette in a normal situation is important but more important is their observance when the situation is adverse.
(d) Words like ‘please’ and ‘thank you’ help us in making our passage through life uneasy.
(e) The law permits anybody to use violence, if another person is discourteous.
Answer:
True statements:
(a) Bitter problems in day-to-day life can be solved by sweet words.
(b) Great wars could have been avoided by a little courtesy.
(c) Observance of etiquette in a normal situation is important but more important is their observance when the situation is adverse.

False statements:
(d) Words like ‘please’ and ‘thank you’ help us in making our passage through life uneasy.
(e) The law permits anybody to use violence, if ; another person is discourteous.

Corrected statements :
(d) Words like ‘please’ and ‘thank you’ help us in making our passage through life easy.
(e) The law does not permit anybody to use violence, if another person is discourteous.

Question (ii)
Select the most appropriate sentences which suggest the theme of the essay.
(a) The essay tells us about courtesy, civility, morality, responsibility and control.
(b) The essay explores the difficulties that can be incurred by an individual when dealing with the public.
(c) One can keep one’s peace of mind without having to lower themselves to the level of the perceived offender.
(d) People with low self-esteem are generally difficult to work with and they look down upon others to get a feeling of superiority.
Answer:
(a) The essay tells us about courtesy, civility, morality, responsibility and control.
(c) One can keep one’s peace of mind without having to lower themselves to the level of the
perceived offender.

(iii)

Question (a)
Find the reasons for the liftman’s uncivilized behaviour.
Answer:
Reasons for the liftman’s uncivilized behaviour when the passenger was rude and ill-mannered towards him:

he was acutely hurt by the slur cast by the passenger on his social status
the passenger’s discourtesy was a wound to his self-respect
he felt insulted by the passenger’s discourtesy.

Question (b)
List the people and their behaviour that made the passenger rude and ill- mannered.

Answer:
The people who made the passenger rude and ill-mannered:
[housemaid] → [cook] → [employer’s wife] → [employer] → [passenger] → [lift-man]

Question (iv)
Good manners are required in our daily life for making our social contacts more cooperative and friendly. Illustrate the behaviour of the polite conductor with different people in various situations.

Answer:

Situation	Behaviour
1. The writer’s sensitive toe was trampled on	The conductor said sorry with an apology and courtesy.
2. In the rainy season dealing with people	He would run up the stairs to give someone the tip that there was “room inside”.
3. Dealing with old people	He was as considerate as a son.
4. Dealing with children	He was as solicitous as a father.
5. Dealing with young people	He always indulged in some merry jest with them.
6. Dealing with a blind man	He set him down safely on the pavement and then took him wherever he wanted to go, after telling the driver to wait for a while.

Question (v)
Discuss and Write the impact of good temper and kindliness on society in the light of the good-mannered conductor.
Answer:
The conductor was always cheerful and kind-hearted to everyone in the bus. This spread to his passengers and they too became cheerful and good-humored. They would naturally pass on this feeling after getting off the bus. Thus, in society, if people are good-tempered, cheerful and kind, it will spread to others and they too will start behaving in a similar manner. This will lead to a happy and compassionate society.

Question (vi)
‘A modest calling can be made dignified by good temper and kindly feeling’. Explain the statement with examples.
Answer:
This means that whatever career or job one has, however simple or modest, it can be made more dignified by behaving in a good- tempered and cheerful manner and with kindliness towards the people one comes in contact with. For example, even a simple job like that of a security guard at a mall can be made pleasant and dignified if the guard smiles and says ‘Thank you’ or ‘Good morning’ every time he/she checks a person.

A sweeper’s job can also be made more dignified if he/she just nods and smiles at passers-by or helps them if they are in need.

Question (vii)
The service of the police is necessary for the implementation of law in our society. Do you think you require this service for a good social environment? Discuss and write.
Answer:
No, we cannot have the police monitoring us for social and moral offences. For example, one cannot be punished if one refuses to smile at an acquaintance or say Thank you’. One cannot be punished if one doesn’t hold the door open for the person who is following.

These are good manners, or courtesy, and they have to be taught right from childhood, and they will change in different cultures and different circumstances. Whether a person follows them or not depends on the individual. However, if these little courtesies are followed, life will become much simpler and more pleasant for everyone.

(A3)

Question (a)
Find out the words in Column B which collocate with the words in Column A:

Answer:

A	B	Answer
regular	meal	regular exercise
mid day	concept	mid-day meal
key	food	key concept
fast	exercise	fast food
try	decorated	try hard
richly	hard	richly decorated
free	jam	free time
traffic	time	traffic jam
social	animal	social justice
wild	justice	wild animal

Question (b)
Learning collocations is essential for making your English sound fluent and natural. Make the following collocations and use them in your own sentences.

Sentences:
(1) BIG:

It was a big mistake to hold a party on a rainy day.
“Did you get a big surprise when you saw me?” asked the little girl to her mother.
There was a big welcome waiting for the winning team.
The hungry beggar prayed that he would get a big meal at the rich man’s home.
Writing the difficult exam was no big deal for the intelligent boy.
Rohan realized that it would be a big challenge for him to win the match.
The discovery of a new element was big news in the scientific community.
Losing the beauty contest was a big shock for the arrogant girl.

(2) WELL :

The well-dressed man jumped over the puddle carefully.
The advice the teacher gave Rita was well-meant, but Rita did not like it.
The cook was happy to see the well-stocked cupboard.
Little Naina was well-pleased with her birthday gift.

Question (ii)
Sometimes while using a word in a sentence, we have to change its word class. we can make several more words from the root word.
we can make several new words from the root word.
I asked Sumit to ……………. my pencil for me. (sharp).
I asked Sumit to sharpen my pencil for me.

Question 1.
Now read the following sentences and use the words given in the brackets. Change the word class and rewrite the sentences.
(a) Leena was eating a very …………. apple and obviously enjoying it. (crunch)
(b) This picture looks …………… (colour)
(c) I’m afraid that your behaviour is just not ……………. (accept)
(d) I like my elder brother. He is very ……………. (help)
Answer:
(a) Leena was eating a very crunchy apple and obviously enjoying it.
(b) This picture looks colourful.
(c) I’m afraid that your behaviour is just not acceptable.
(d) I like my elder brother. He is very helpful.

Complete the following table. Put a cross if a word class does not exist.

Question (iii)
Write appropriate expressions and words you have to use while facing an interview :
Answer:
(a) May I come in?
(b) May I have a seat?
(c) Thank you.
(d) I’m sorry, but I did not catch what you said.
(5) Please let me know

Question (b)
You are writing a letter of complaint. List the proper expressions that you would like to write.
Answer:

I disagree.
I’m sorry to say that….
I would like to suggest….
This was not expected from a company like yours.
Please replace the defective piece as soon as possible.

Question (iv)
Distinguish between a legal offence and a moral offence on the basis of the extract.

Answer:

Legal offence	Moral offence
Burglary	Rude behaviour
Assault	Discourtesy
Battery	Haughtiness
	Laceration of one’s feelings

Question (v)
Find out the meaning of the phrase ‘give and take’ and use it in your own sentence.
Answer:
give-and-take – Meaning: exchange of ideas Sentence – The TV stars engaged in an interesting give-and-take which was enjoyed by the audience.

Question (vi)
Complete the table with polite expressions that we must use in our day-to-day life:

Answer:

Don’ts	Dos
I want a cup of tea.	I would like to have a cup of tea.
Send me the mail.	Please send me the mail.
Go away or leave me alone.	Please let me be by myself.
You are wrong.	Are you sure you’re right?
That’s a bad idea.	That is not a very good idea, is it?
Your work isn’t good.	Your work can do with some improvement

(A4)

Question (i)
Edit the given paragraph using a/ an/the wherever necessary:
Rakesh is a/an ideal son who remains devoted to his father as he grows professionally to become a/the famous doctor. As his father grows old, he takes care to spend time with his father, bringing him tea in a/the morning and taking him out for a/the walk in an/the evening.
Answer:
Rakesh is an ideal son who remains devoted to his father as he grows professionally to become a famous doctor. As his father grows old, he takes care to spend time with his father, bringing him tea in the morning and taking him out for a walk in the evening.

Question (ii)
Spot the errors in each of the following sentences and correct the incorrect ones:

Question (a)
Radha brought pens and distributed them between her five children.
Answer:
Radha bought pens and distributed them among her five children.

Question (b)
Jayshree and Sujata sat besides each other in complete silence.
Answer:
Jayshree and Sujata sat beside each other in complete silence.

Question (c)
His best friend Vijay was blind within one eye.
Answer:
His best friend Vijay was blind in one eye.

Question (d)
One could dare to encroach on his rights.
Answer:
One could not dare to encroach on his rights.

Question (e)
She was taken with surprise when she saw the famous Taj Mahal.
Answer:
She was taken by surprise when she saw the famous Taj Mahal.

Question (f)
It is not possible to exchange the goods once the sale has been completed.
Answer:
It is not possible to exchange goods once the sale has been completed, (‘the’ is deleted.)

Question (g)
Dr. Sengupta has been trying to master the craft for the last five years.
Answer:
No error in this sentence.

Question (h)
The top-ranking candidates will be appointed in senior jobs in banks.
Answer:
The top-ranking candidates will be appointed | to senior jobs in banks.

Question (i)
She knows very well what is expected from her but she is unable to perform.
Answer:
She knows very well what is expected of her but she is unable to perform.

Question (j)
They will put on a note in this regard for your consideration.
Answer:
They will put up a note in this regard for your consideration.

Question (iii)
Read the following.
Santosh purchased a computer. He read the operating manual and followed the instructions.
(a) He linked the monitor, keyboard and printer.
(b) He plugged in the main cable.
(c) He switched on the monitor at the back.
(d) When the light appeared on the screen, he placed the Day Disk in Drive A.
(e) He pushed in the disk until the button clicked out.
(It took about 30 seconds for the computer to load the program.)
(f) He pressed the Drive button and the disk shot out.
(g) He replaced the Day Disk with the Document Disk.
(h) He pressed function key 7.
Convert these sentences into passive voice by filling in the blanks.

Firstly the monitor, keyboard and printer were linked up. Then the main cable was plugged in. The monitor was switched on at the back. When the light appeared on the screen, the Day Disk was placed in Drive A. The disk was pushed in until the button clicked out. It took the computer 30 seconds to load the program. The drive button was pressed and the disk shot out. The Day Disk was replaced with the Document Disk. Finally, the function key 7 was pressed. The word processor was then ready to use.

(A5)

Question (i)
Write a speech on ‘Courtesy is the light of life’ with the help of the following points.
(a) People have a good impression of you.
(b) You will be acknowledged and appreciated by all.
(c) You will he happier and contented with life.
Answer:
Courtesy is the light of life
Dear friends,

Good morning. You may be surprised with the topic I have chosen for this speech, for today the word ‘Courtesy’ seems to be an old-fashioned word for us. But it is really the light of life. I, Shivam Goswami, would like to say a few words on why I think so.

First of all, what does courtesy mean? It means good manners and polite behaviour. It means being kind and compassionate towards someone. When you are courteous, people have a good impression of you; but that is not the reason for being courteous. Politeness should be real, and not artificial.

A courteous person will be appreciated by all. People will like to spend time with him/her and find pleasure in the person’s company. Someone may ask ‘What is courteous behaviour’? Saying simple words like ‘Please’, ‘Thank you’, ‘Excuse me’ and ‘Sorry’ is courteous behaviour. Helping a person who has fallen is courteous behaviour. Holding the lift door open for someone is courteous behaviour.

When a person is courteous, people are automatically courteous in return. This leads to a more polite and happier society. As I conclude, I would like to ask all of you to do something for a week: Be courteous. Then you will see the returns and realize the truth of what I am saying. Thank you for listening to me so patiently. Bye.

Question (ii)
‘Manners maketh man’ – Expand the idea in your own words with proper examples.
Answer:
Manners maketh man

‘Manners maketh Man’ : so goes a famous saying. In the world of today, people are judged by their manners and conduct. Manners distinguish us from animals, and make us human. A person who is courteous and considerate towards others is said to possess good manners. Such a person is respectful to his superiors, courteous to his equals and sympathetic towards his subordinates. He always shows concern for the well-being and comfort of others. He uses words like ‘Please’, ‘Thank you’ and ‘Sorry’ while talking to others; he helps senior citizens and those in need.

Everyone likes a person who speaks and behaves politely and treats others respectfully. Good manners cost practically nothing but can buy everything. They win us friends and help us influence people. They make the world a happier place to live in by reducing friction and avoiding tension.

When we meet a person for the first time, it is the person’s courtesy which impresses us deeply. Good manners are generally taught by parents at home, and by teachers in school. Manners that are learnt during childhood generally remain with us throughout our lives. They become a part of our personality. Hence, it is desirable that good manners are instilled in children when they are very young, so that they grow up to become courteous, considerate adults.

(A6)

Question (i)
Read A. G. Gardiner’s essay “The Open Window’ and compare its theme with the essay ‘On Saying “Please.”

Question (ii)
‘Nothing clears up my spirits like a fine day’ – Keats. Collect information of the poet Keats and write it in your notebook.

(A7)

Question (i)
Soft skills are required in all walks of life including careers and industries. They are increasingly becoming the essential skills of today’s workforce. Soft skills are an integral part of finding, attracting and retaining clients also. Highly developed presentation skills, networking abilities, and etiquette awareness can help you win new clients and gain more work. The following are considered the most important soft skills.
image

Question (ii)
Following are some of the institutions where you will get the courses related to soft skills.
(a) Indian Institute of Management, Ahmedabad, Gujarat
(b) Indian School of Business Management, Hyderabad
(c) XLRI – Xavier School of Management, Jamshedpur
(d) Indian Institute of Foreign Trade, New Delhi
Jobs available at –

Customer service centre
Management schools
Hotel industry, etc.

Yuvakbharati English 12th Digest Chapter 1.2 On Saying “Please” Additional Important Questions and Answers

Read the extract and complete the activities given below.:

Global Understanding:

Question 1.
Read the following sentences and find out True and False sentences. Correct the false sentences:
1. The liftman invited the passenger into the lift.
2. If you knock down a burglar, the law will acquit you.
3. There is no legislation against bad manners.
4. The complainant had to pay a fine.
Answer:
True sentences:
2. If you knock down a burglar, the law will acquit you.
3. There is no legislation against bad manners.

False sentences:
1. The liftman invited the passenger into the lift.
4. The complainant had to pay a fine,

Corrected sentences:
1. The liftman threw the passenger out of the lift.
4. The liftman had to pay a fine.

Question 2.
Explain the penalty, if any, that one has to pay if one is rude or boorish.
Answer:
There is no penalty to pay if one is rude or boorish except the penalty of being called a ill-mannered person.

Question 3.
The behaviour of the people who made the passenger rude and ill-mannered:
Answer:

Question 4.
Complete the following:
(The answers are given directly and underlined.)
Answer:

The first requirement of civility is that we should acknowledge a service.
The Underground Railway Company insists that their employees are civil.
The words which make life smooth are ‘please’ and ‘thank you’.
The job of a bus conductor is very difficult and sometimes painful.

Question 5.
Tick mark the correct words:
(The answers are marked directly.)
Answer:

The author finally found/did not find the money for the ticket.
The author thought he had left home with/ without any money.
The conductor gave/did not give the author a ticket.
The author was pleased/displeased with the conductor.

Question 6.
Complete the web by choosing the correct words from the brackets that describe the conductor: (mean cheerful considerate grumpy patient solicitous impatient polite irritable good-tempered haughty good-natured kind)
Answer:

Question 7.
Complete the following :
(The answers are given directly and underlined.)
Answer:

A modest career can he made dignified by good temper and kindly feeling.
The law can only protect us against material) attack.
The narrator says he does not want to apologise for praising an unknown bus conductor.
A man who is polite may lose material advantage but he always has the spiritual victory.

Complex Factual:

Question 1.
Explain what the liftman wanted the passenger to do, and what happened afterwards.
Answer:
The passenger, on entering the lift, said ‘Top’. The liftman wanted him to say ‘Top please’. The passenger refused to do so. The liftman, instead of taking him to the top floor, threw him out of the lift.

Question 2.
Explain the sentence: The pain of a kick on the shins soon passes away but the pain of a wound to our self-respect or our vanity may poison a whole day.
Answer:
This means that if we are physically attacked i and injured, the pain of the wounds will soon heal and be forgotten. But if our self-respect or pride is hurt, it may poison our lives and behaviour for a much longer time.

Question 3.
It is not possible for the law to become the guardian of our private manners. Explain.
Answer:
The area of moral offences is quite vast and no laws or commandments can cover this area. In addition, social civilities, speech and manners are of so many types and the interpretation of these (whether they are good or bad) is so different that no court could administer a law which governed them. Hence, it is not possible for the law to become the guardian of our private manners.

Question 4.
Mention a couple of ways to keep the machine of life oiled and running sweetly.
Answer:
We can keep the machine of life oiled and running sweetly by using courteous words like ‘Please’ and ‘Thank you’ to acknowledge a service.

Question 5.
Complete the following:
(The answer is given directly and underlined.)
Answer:
The public owes much to the Underground Railway Company because they insist on a certain standard of civility in their employees, and take care that the standard is observed.

Question 6.
Complete the table:
Answer:

The words	Who said!	To whom	When
1. “I haven’t a copper on me.”	The narrator	The conductor	When the conductor and the narrator found that he had left home without any money in his pocket.
2. “Oh, you’ll see me some day alright.”	The conductor	The narrator	When the narrator address) he could send the borrowed asked where (to which money.
3. “Where shall I send the fare?”	The narrator	The conductor	When the narrator wanted to repay the ticket money to the conductor.
4. “Where do you want to go?”	The conductor	The narrator	When the narrator explained that he did not have any money on him, and the conductor

Question 7.
Write the narrator’s opinion about how the liftman should have dealt with the passenger’s uncivility. Give reasons for the same.
Answer:
In the opinion of the writer, the liftman, instead of throwing the passenger out of the lift, should have treated him with elaborate politeness. He would have then had the victory not only over the rude passenger, but also over himself, and that was the spiritual victory that was more important. His revenge would then have been more subtle and effective.

Inference/Interpretation/Analysis :

Question 1.
Name the ‘unpleasant specimen’ mentioned in the extract and describe his behaviour.
Answer:
The ‘unpleasant specimen’ mentioned in the extract is the type of bus conductor who regards his passengers as natural enemies whose chief purpose on the bus is to cheat him, and who can only be kept honest by using a loud voice and an aggressive manner.

Question 2.
Describe the stale old trick, according to the conductor.
Answer:
Pretending that you have forgotten your purse at home, and hence do not have the fare for the ticket is a stale old trick, according to the conductor. (The conductor does not say this the narrator only imagines that he may do so.)

Question 3.
Describe the reactions of the bus conductor.
Answer:
No, the conductor did not think that the narrator was dishonest. He cheerfully accepted what the narrator said without doubting him and offered him a free ticket.

Question 4.
Describe the experience which made the narrator comfortable in the bus.
Answer:
The conductor had trampled on the narrator’s sensitive toe, causing him pain and agony. However, the conductor had then explained matters and apologized so profusely that the narrator forgot his pain and anger. After this experience, the narrator always observed his constant good nature and cheerful behaviour with pleasure and felt comfortable in his presence.

Question 5.
Describe the narrator’s justification of his praise of the conductor.
Answer:
The narrator says that if the famous poet Wordsworth could gain wisdom from a poor leech-gatherer, he sees no reason why ordinary people should not take lessons on conduct from a bus conductor, who shows how a modest job can be made more dignified by behaving in a good-tempered and cheerful manner and with kindliness towards the people one comes in contact with.

Personal Response:

Question 1.
Describe a person you have come across who is always polite and helpful. What do you think about him/her?
Answer:
The security guard of our building is always polite and helpful. He will help senior citizens get in and out of their cars or into the lift; he will help any person who has heavy bags. He also replies politely to any question asked by anyone. We all like him very much and often share our chocolates and biscuits with him. We also give him books, stationery and toys for his little child.

Question 2.
Describe a pleasant/unpleasant experience you have had with a bus conductor.
Answer:
This is an experience I had when I was new to Mumbai. I got into a bus and asked the conductor for a ticket to Dadar. The conductor shook his head and told me that I had got into the bus going in the wrong direction. He patiently explained that I would have to get off at the next stop, cross the road, and catch a bus having the same number but going in the opposite direction. He even pointed out the bus stop to me. Though I felt a bit embarrassed, I thanked him for his kindness.

Question 3.
Give your opinion about the conductor’s behaviour.
Answer:
The conductor was really a good and kind human being who saw the best in everyone and believed everyone. He was ready to pay the fare for the narrator’s ticket himself, even though he was not sure whether it would be returned. It is difficult to find such generous and helpful people in the world today, and it leaves a very pleasant feeling in the heart when you do.

Language Study:

Question 1.
The law does not compel me to say ‘Please’.
(Rewrite as an interrogative sentence.)
Answer:
Does the law compel me to say ‘Please’?

Question 2.
It was a question of ‘Please’.
(Add a question tag.)
Answer:
It was a question of ‘Please’, wasn’t it?

Question 3.
It will permit me to retaliate with reasonable violence.
(Pick out the finite and non-finite verbs.)
Answer:
will permit – finite verb;
to retaliate – non-finite verb (infinitive)

Question 4.
The pain of a wound to our self-respect may poison a whole day.
(Pick out the auxiliary and state its function.)
Answer:
may – possibility

Question 5.
For there are few things more catching than bad temper.
(Write the part of speech of the underlined word.)
Answer:
Gerund

Question 6.
Bad manners probably do more to poison the stream of general life than all the crimes in the calendar. (Rewrite in the present perfect tense.)
Answer:
Bad manners have done probably more to poison the stream of general life than all the crimes in the calendar.

Question 7.
There is a social practice much older and much more sacred than any law which enjoins us to be civil.
(Rewrite using ‘not only … but also… ’)
Answer:
There is a social practice not only much older but also much more sacred than any law which enjoins us to be civil.

Question 8.
Most people will have a certain sympathy with him. (Rewrite using the verb form of the underlined word.)
Answer:
Most people will sympathize with him.

Question 9.
Here and there you will meet an unpleasant specimen who regards the passengers as his natural enemies. (Replace the verb in the future tense with a modal auxiliary showing possibility.)
Answer:
Here and there you might meet an unpleasant specimen who regards the passengers as his natural enemies.

Question 10.
I had left home without any money in my pocket. (Pick out the verb and state the tense.)
Answer:
had left-past perfect tense.

Question 11.
I know that stale old trick.
(Rewrite beginning ‘That stale old trick ’.)
Answer:
That stale old trick is known to me.

Question 12.
I said it was very kind of him.
(Identify the clauses.)
Answer:
I said – main clause
it was very kind of him – subordinate noun clause

Question 13.
I began to observe him whenever I boarded his bus. (Pick out the subordinate clause and state the type.)
Answer:
subordinate clause – whenever I boarded his bus; adverb clause of time.

Question 14.
He seemed to have an inexhaustible fund of patience and a gift for making his passengers comfortable. (Rewrite using ‘as well as…’)
Answer:
He seemed to have an inexhaustible fund of patience as well as a gift for making his passengers comfortable.

Question 15.
In lightening their spirits he lightened his own task. (Rewrite using the verb form of the underlined word.)
Answer:
When he lightened their spirits he lightened his own task.

Question 16.
A very modest calling may be dignified by good temper and kindly feeling. (Rewrite as an interrogative sentence.)
Answer:
Can’t a very modest calling be dignified by good temper and kindly feeling?

Question 17.
“I never give the wall to a scoundrel,” said a man who met Chesterfield one day in the street. “I always do,” said Chesterfield, stepping with a bow into the road. (Rewrite using reported speech.)
Answer:
A man who met Chesterfield one day in the street said that he never gave the wall to a scoundrel. Chesterfield, stepping with a bow into the road, replied that he always did.

Question 18.
The polite man may lose the material advantage, but he always has the spiritual victory. (Rewrite beginning ‘Though’)
Answer:
Though the polite man may lose the material advantage, he always has the spiritual victory.

Vocabulary:

Find out the meanings of the following phrases and use them in your own sentences.

Question 1.
knock someone down –
Answer:
Meaning: to hit someone forcefully so that he/she falls down
Sentence: The young boy was so angry with the bully that he knocked him down.

Question 2.
to comply with :
Answer:
Meaning: to obey.
Sentence: We must comply with the laws of the country we live in.

Question 3.
Find out 2 words with prefixes and 2 with suffixes from the extract and write them down.
Answer:
1. Words with prefixes : discourtesy, uncivil.
2. Words with suffixes : instruction, reasonable.

Question 4.
Complete the following:
Answer:

A liftman is a person who is employed to operate a lift.
An assailant is a person who attacks another person.
A complainant is a person who makes a formal complaint in a law court.
A burglar is a person who illegally enters houses and steals things.

Question 5.
Write the meanings of the following words :

redress
henpecked
black eye.

Answer:

redress – to set right to remedy.
henpecked – being controlled by and frightened of one’s wife.
black eye – an area of skin around the eye that has gone dark because it has been hit.

Question 6.
Use the phrase ‘a black eye’ in your own sentence.
Answer:
When I saw my friend with a black eye, I knew that he had been in a fight with someone.

Question 7.
Find out 2 words with suffixes and 2 compound words from the extract and write them down.
Answer:
1. words with suffixes: vanity, really.
2. Compound words: breakfast, housemaid.

Question 8.
Write the meaning of the following words:

endorse
verdict
resentment
calling

Answer:

endorse – express support
verdict – judgement
resentment – anger
calling – vocation or profession.

Question 9.
Find out 2 words with suffixes from the extract and write them down.
Answer:
Words with suffixes : sympathy, requirement.

Question 10.
Find out two words with prefixes and two with suffixes from the extract and write them down.
Answer:
1. Words with prefixes: unfriendliness, inconvenience
2. Words with suffixes: existence, discovery

Question 11.
Pick out four adverbs of manner from the extract.
Answer:
coldly, cheerfully, luckily, easily.

Question 12.
Write the meanings of the followings words:

countenance
treading
assured (someone)
benediction
uncouth

Answer:

countenance – face.’
treading – walking on.
assured (someone) – made something certain to someone.
benediction – a blessing.
uncouth – impolite, unrefined.

Question 13.
Find out 2 words with prefixes and 2 with suffixes from the extract and write them down.
Answer:
1. words with prefixes: inexhaustible, unusually
2. words with suffixes: investment, cheerful

Question 14.
Write the meaning of ‘moral affront’.
Answer:
moral affront: a deliberate offence or insult to one’s dignity or self-respect.

Question 15.
Find out the meaning of the following phrase and use it in your own
sentence: lower than the angels
Answer:
lower than the angels – Meaning : less than perfect
Sentence: The unexpected behaviour of the religious men was somewhat lower than the angels.

Question 16.
Write four words with suffixes from the extract and write them down.
Answer:
agreement, politeness, institution, sweeten.
Note: Students can find more words on their own.

Vocabulary:

A Collocation is a combination of words in a language that often go together. They habitually occur together and hence convey some meaning by association, e.g. early morning, hot dinner, fast train.

Non-Textual Grammar:

Do as directed:

Question 1.
Hearing the sound of music from a side street, Mona had an idea.
(Rewrite as a compound sentence.)
Answer:
Mona heard the sound of music from a side-street and had an idea.

Question 2.
Siddharth could not ask his father for a cricket bat.
(Rewrite using the antonym of ‘able’.)
Answer:
Siddharth was unable to ask his father for a cricket bat.

Question 3.
“I will try,” the lady smiled.
(Rewrite in indirect speech.)
Answer:
The lady smiled and said that she would try.

Spot the error in the following sentences and rewrite them correctly:

Question 1.
I picked some of the lovely, tasty fruits and had eaten my fill of them.
Answer:
I had picked some of the lovely, tasty fruits and had eaten my fill of them.

Question 2.
I miss my friends a lots.
Answer:
I miss my friends a lot.

12th Std English Questions And Answers:

12th Biology Chapter 8 Exercise Respiration and Circulation Solutions Maharashtra Board

January 8, 2025January 7, 2025 by Prasanna

Balbharti Maharashtra State Board 12th Biology Textbook Solutions Chapter 8 Respiration and Circulation Textbook Exercise Questions and Answers.

Respiration and Circulation Class 12 Exercise Question Answers Solutions Maharashtra Board

Class 12 Biology Chapter 8 Exercise Solutions Maharashtra Board

Biology Class 12 Chapter 8 Exercise Solutions

1. Multiple choice questions

Question 1.
The muscular structure that separates the thoracic and abdominal cavity is …………………..
(a) pleura
(b) diaphragm
(c) trachea
(d) epithelium
Answer:
(b) diaphragm

Question 2.
What is the minimum number of plasma membrane that oxygen has to diffuse across to pass from air in the alveolus to haemoglobin inside a R.B.C.?
(a) two
(b) three
(c) four
(d) five
Answer:
(a) two

Question 3.
…………………. is a sound producing organ.
(a) Larynx
(b) Pharynx
(c) Tonsils
(d) Trachea
Answer:
(a) Larynx

Question 4.
The maximum volume of gas that is inhaled during breathing in addition to T.V. is …………………..
(a) residual volume
(b) IRV
(c) GRV.
(d) vital capacity
Answer:
(b) IRV

Question 5.
………………….. muscles contract when the external intercostals muscles contract.
(a) Internal abdominal
(b) Jaw
(c) Muscles in bronchial walls
(d) Diaphragm
Answer:
(d) Diaphragm

Question 6.
Movement of cytoplasm in unicellular organisms is called …………………..
(a) diffusion
(b) cyclosis
(c) circulation
(d) thrombosis
Answer:
(b) cyclosis

Question 7.
Which of the following animals do not have closed circulation?
(a) Earthworm
(b) Rabbit
(c) Butterfly
(d) Shark
Answer:
(c) Butterfly

Question 8.
Diapedesis is performed by …………………..
(a) erythrocytes
(b) thrombocytes
(c) adipocytes
(d) leucocytes
Answer:
(d) leucocytes

Question 9.
Pacemaker of heart is …………………..
(a) SA node
(b) AV node
(c) His bundle
(d) Purkinje fibers
Answer:
(a) SA node

Question 10.
Which of the following is without nucleus?
(a) Red blood corpuscle
(b) Neutrophil
(c) Basophil
(d) Lymphocyte
Answer:
(a) Red blood corpuscle

Question 11.
Cockroach shows which kind of circulatory system?
(a) Open
(b) Closed
(c) Lymphatic
(d) Double
Answer:
(a) Open

Question 12.
Diapedesis can be seen in …………………..
(a) RBC
(b) WBC
(c) Platelet
(d) neuron
Answer:
(b) WBC

Question 13.
Opening of inferior vena cava is guarded by …………………..
(a) bicuspid valve
(b) tricuspid valve
(c) Eustachian valve
(d) Thebesian valve
Answer:
(c) Eustachian valve

Question 14.
…………………. wave in ECG represent atrial depolarization.
(a) P
(b) QRS complex
(c) Q
(d) T
Answer:
(a) P

Question 15.
The fluid seen in the intercellular spaces in Human is …………………..
(a) blood
(b) lymph
(c) interstitial fluid
(d) water
Answer:
(b) lymph

2. Match the columns

Question 1.
Respiratory surface Organism

Respiratory surface	Organism
(1) Plasma membrane	(a) Insect
(2) Lungs	(b) Salamander
(3) External gills	(c) Bird
(4) Internal gills	(d) Amoeba
(5) Trachea	(e) Fish

Answer:

Respiratory surface	Organism
(1) Plasma membrane	(d) Amoeba
(2) Lungs	(c) Bird
(3) External gills	(b) Salamander
(4) Internal gills	(e) Fish
(5) Trachea	(a) Insect

3. Very Short Answer Questions

Question 1.
Why does trachea have ‘C’-shaped rings of cartilage?
Answer:
Trachea is supported by ‘C’-shaped rings of J cartilage which prevent it from collapsing and always keep it open.

Question 2.
Why is respiration in insect called direct respiration?
Answer:
Respiration in insect is called direct because tracheal tubes exchange O₂ and CO₂ directly with the haemocoel which then exchange them with tissues.

Question 3.
Why is gas exchange very rapid at alveolar level?
OR
Why does gas exchange in the alveolar region very rapid?
Answer:
Gas exchange is very rapid at alveolar level because numerous alveoli (about 700 millions) in the lungs provide large surface area for gaseous exchange.

Question 4.
Name the organ which prevents the entry of food into the trachea while eating.
Answer:
Epiglottis prevents the entry of food into trachea while eating.

4. Short Answer Questions

Question 1.
Why is it advantageous to breathe through the nose than through the mouth?
Answer:
Breathing through nose is better than breathing through the mouth because of the following reasons:

The nostrils are smaller than the mouth so air exhaled through the nose creates a backflow of air into the lungs.
As we exhale more slowly through the nose than we do through the mouth, the lungs have more time to extract oxygen from the air that we have already taken in.
The hairs inside nostrils filter any dust particles and microbes in the air and it only lets the clean air pass through.
The air gets warm and humidified in nostrils as it passes into our bodies.
Moreover breathing through the mouth can dry the oral cavity and lead to bad breath, gum disease and tooth decay.

Question 2.
Identity the incorrect statement and correct it.
(a) A respiratory surface area should have a. large surface area.
(b) A respiratory surface area should be kept dry.
(c) A respiratory surface area should be thin, may be 1 mm or less.
Answer:
Statement (a) and statement (c) are correct whereas statement (b) is incorrect. A respiratory surface area should be kept moist, is the correct statement.

Question 3.
Given below are the characteristics of some modified respiratory movement. Identify them.
a. Spasmodic contraction of muscles of expiration and forceful expulsion of air through nose and mouth.
Answer:
Sneezing

b. An inspiration followed by many short convulsive expiration accompanied by facial expression.
Answer:
Laughing, Crying.

Question 4.
Blood plasma.
Answer:

Plasma is a straw coloured, slightly alkaline viscous fluid part of the blood, having 90-92% water and 8-10% soluble proteins.
Serum albumin, serum globulin, heparin, fibrinogen and prothrombin are the plasma proteins which form 7% of the plasma.
Glucose, amino acids, fatty acids and glycerol are the nutrients dissolved in plasma.
Nitrogenous wastes (urea, uric acid, . ammonia and creatinine) and respiratory gases (oxygen and carbon dioxide) is present in plasma.
Enzymes and hormones too are transported Ada plasma.
Inorganic minerals are also present in plasma such as bicarbonates, chlorides, phosphates and sulphates of sodium, potassium, calcium and magnesium.

Question 5.
Blood clotting/Coagulation of blood.
OR
Explain blood clotting in short.
Answer:

The process of converting the liquid blood into a semisolid form is called blood clotting or coagulation.
The process of clotting may be initiated by contact of blood with any foreign surface (intrinsic process) or with damaged tissue (extrinsic process).
Intrinsic and extrinsic processes involve interaction of various substances called clotting factors by a step wise or cascade mechanism.
There are in all twelve clotting factors numbered as I to XII (factor VI is not in active use).
Interaction of these factors in a cascade manner leads to formation of enzyme, Thromboplastin which helps in the formation of enzyme prothrombinase.
Prothrombinase inactivates heparin and also converts inactive prothrombin into active thrombin.
Thrombin converts soluble blood protein- fibrinogen into insoluble fibrin. Fibrin forms a mesh in which platelets and other blood cells are trapped to form the clot.
These reactions occur in 2 to 8 minutes. Therefore, clotting time is said to be 2 to 8 minutes.

Question 6.
Describe pericardium.
Answer:

Pericardium is the double layered peritoneum that encloses the heart. It consists of two layers, viz. fibrous pericardium and serous pericardium.
Fibrous pericardium is the outer layer having tough, inelastic fibrous connective tissue whereas serous pericardium is the v inner double layered membrane. It has in turn an outer parietal layer and inner visceral layer.
Parietal layer of serous pericardium lies on the inner side of fibrous pericardium.
Visceral layer also known as epicardium adheres to heart and thus forms outer covering over the heart.
There is a pericardial fluid in the pericardial space which is present in between the parietal and visceral layers of serous pericardium.

Question 7.
Describe valves in the human heart.
Answer:
Human heart has following main valves:

Tricuspid valve : Tricuspid valve is present between the right atrium and right ventricle. It has three cusps or flaps. It prevents the backflow of blood into right atrium.
Bicuspid valve : Bicuspid valve, also called mitral valve is present between the left atrium and left ventricle. It has two flaps. It prevents the backflow of blood in left atrium. Both tricuspid and bicuspid valves are attached to papillary muscles with tendinous chords or chordate tendinae to prevent valves from turning back into atria at the time of systole.
Semilunar valve : These are present at the opening of pulmonary artery and systemic aorta. They prevent the back flow of blood when ventricles undergo systole.
Thebesian valve : Thebesian valve is present at the opening of coronary sinus.
Eustachian valve : Eustachian valve is present at the opening of inferior vena cava.

Question 8.
What is the role of papillary muscles and chordae tendinae in human heart?
Answer:

Papillary muscles are large and well- developed muscular ridges present along the inner surface of the ventricles.
Bicuspid and tricuspid valves are attached to papillary muscles of ventricles by chordae tendinae.
Chordae tendinae are inelastic fibres present in the lumen of ventricles.
The chordae tendinae prevent the valves from turning back into the atria during the contraction of ventricles and regulate the opening and closing of bicuspid and tricuspid valves.

Question 9.
Explain in brief the factors affecting blood pressure.
Answer:

Cardiac output : Normal cardiac output is 5 lit/min. Increase in cardiac output increases systolic pressure.
Peripheral resistance : Peripheral resistance depends upon the diameter of blood vessels. Decrease in diameter of arterioles and capillaries under the effect of vasopressin cause increase in peripheral resistance and thereby increase in blood pressure.
Blood volume : Loss of blood in accidents decreases blood volume and thus cause decrease in blood pressure.
Viscosity of blood : Blood pressure is directly proportional to viscosity of blood.
Age : Blood pressure increases with age due to increase in inelasticity of blood vessels.
Venous return : Amount of blood brought to the heart via the veins per unit time is called the venous return and it is directly proportional to blood pressure.
Length and diameter of blood vessels : Blood pressure is directly proportional to the total length of the blood vessel. Blood pressure can also be affected by vasoconstriction or vasodilation.
Gender : Females have slightly lower BP than males of her age before menopause. However, the risk of high B. P increases in the females after menopause sets in.

5. Give Scientific Reason

Question 1.
Closed circulation is more efficient than open circulation.
Answer:

Closed circulation considerably enhances the speed, precision and efficiency of circulation.
The blood flows more rapidly, it takes less time to circulate through the closed system and return to the heart.
This fastens the supply and removed of materials to and from the tissues by the blood as compared to open circulation.
In open circulation, there are no blood vessels such as arteries or veins, to pump the blood.
Therefore, the blood pressure is very low.
Organisms with an open circulatory system typically have a relatively high volume of hemolymph and low blood pressure. Closed circulation is thus more efficient than open circulation.

Question 2.
Human heart is called as myogenic and autorhythmic?
Answer:

The heart shows auto rhythmicity because the impulse for its rhythmic movement develops inside the heart. Such heart is called myogenic.
Some of the cardiac muscle fibres become auto rhythmic (self-excitable) and start generating impulse during development.
These autorhythmic fibres perform two important function, viz. acting as a pacemaker and setting the rhythm for heart.
They also form conducting system for conduction of nerve impulses throughout the heart muscles.

Question 3.
In human heart, the blood flows only in one direction.
Answer:

In veins there are valves, which prevent the back flow of the blood.
In arteries, blood flows with unidirectional pressure.
Hence the circulation takes place only in one direction.

Question 4.
Arteries are thicker than veins.
Answer:

Arteries have relatively thick walls to enable them to withstand the high pressure of blood ejected from the heart.
Arteries expand when the pressure increases as the heart pushes blood out but then recoil (shrink) Wn the pressure decreases when the heart relaxes between heartbeats.
This expansion and recoiling occurs to maintain a smooth blood flow.
Veins, on the other hand, have thinner walls and larger lumen veins have no need for thick walls as then need not have to withstand high pressure like arteries.
Moreover, as veins transport relatively low pressure blood, they are commonly equipped with valves to promote the unidirectional flow of blood towards the heart.

Question 5.
Left ventricle is thick than all other chambers of heart.
OR
Left ventricle has thicker wall than the right ventricle.
Answer:

Left ventricle pumps oxygenated blood to all parts of the body. Therefore, there is greater pressure from the blood in left ventricle.
Right ventricle sends deoxygenated blood to lungs for oxygenation. This does not put more pressure and lungs are in vicinity of the heart.
Due to these functional differences between the two ventricles, left ventricle has thicker wall than that of the right ventricle.

6. Distinguish Between

Question 1.
Open circulation and Closed circulation
Answer:

Open circulation	Closed circulation
1. In open circulation, blood flows through large open spaces and channels called lacunae and haemocoels among the tissues.	1. In closed circulation, blood flows through a network of blood vessels all over the body.
2. Tissues are in direct contact with the blood.	2. Blood does not come in direct contact with tissue.
3. Blood flows with low pressure and usually does not contain any respiratory pigment like haemoglobin.	3. Blood flows with high pressure and contains respiratory pigment like haemoglobin.
4. Exchange of material takes place directly between blood and cells or tissues of the body.	4. Exchange of material takes place between blood and body tissues through an intermediate fluid called lymph.
5. Volume of blood flowing through a tissue cannot be controlled as blood flows out in open space.	5. Volume of blood can be regulated by the contraction and relaxation of the smooth muscles of the blood vessels.
6. Open circulatory system is found in arthropods and some molluscs.	6. Closed circulatory system is found in annelids, echinoderms and all vertebrates.

Question 2.
Arteries and veins.
Answer:

Arteries	Veins
1. The blood vessels that arise from the heart and carry blood away from heart are called arteries.	1. The blood vessels that bring blood to the heart are called veins.
2. Arteries are thick walled blood vessels, situated in deep layers in the body.	2. Veins cure thin walled blood vessels, situated superficially in the body.
3. Arteries do not have valves.	3. Veins have valves.
4. Tunica adventitia, the outermost layer of arteries is thick and elastic.	4. Tunica externa, the outermost layer of veins is thin.
5. Tunica media is very thick and contain elastic fibres.	5. Tunica media is thin layer and contain involuntary muscle fibres.
6. The lumen of arteries is small.	6. The lumen of the veins is very spacious.
7. With the exception of pulmonary arteries, all other arteries carry oxygenated blood.	7. With the exception of pulmonary veins, all other veins carry deoxygenated blood.
8. Blood in the arteries show high blood pressure.	8. Blood in the veins show lesser blood pressure.

Question 3.
Blood and Lymph.
Answer:

Blood	Lymph
1. Contains blood plasma with proteins and all three types of blood cells namely RBCs, WBCs and blood platelets.	1. Contains blood plasma without blood proteins, RBCs and platelets and contains lymphocytes.
2. Red in colour due to presence of RBCs.	2. Light yellow in colour and does not contain RBCs.
3. Carries oxygen in the body.	3. Does not carry oxygen.
4. The flow of blood in blood vessels is fast.	4. The flow of lymph in lymph capillaries is slow.
5. Lymphocytes are present.	5. Lymphocytes are present, more in number than those present in the blood.

Question 4.
Blood capillary and Lymph capillary.
Answer:

Blood capillary	Lymph capillary
1. Reddish, easy to observe.	1. Colourless, difficult to observe.
2. Joined to arterioles at one end and to venules at another end.	2. Blind (closed at the tip).
3. Narrower than lymph capillaries.	3. Wider than blood capillaries.
4. Wall consists of normal endothelium and basement membrane.	4. Wall consists of thin endothelium and poorly developed basement membrane.
5. Contains red blood.	5. Contains colourless lymph.
6. Have relatively high pressure.	6. Have relatively low pressure.

Question 5.
Intrinsic and Extrinsic process of clotting.
Answer:

Intrinsic process	Extrinsic process
1. The intrinsic pathway requires only clotting factors found within the blood itself – in particular, clotting factor XII (Hageman factor) from the platelets.	1. The extrinsic pathway is initiated by factors external to the blood, in the tissues adjacent to damaged blood vessel – in particular, it is initiated by clotting factor III, thromoboplastin from the damaged tissues.
2. It is a longer, multistep process and it takes a little longer for the blood to clot by this mechanism.	2. It involves fewer chemical reaction steps and produce a clot a little more quickly than the intrinsic pathway.

7. Long Answer Questions

Question 1.
Smita was working in a garage with the doors closed and automobiles engine running. After some time she felt breathless and fainted. What would be the reason? How can she be treated
OR
While working with the car engine in a closed garage, John suddenly felt dizzy and fainted what is the possible reason?
Answer:

As Smita and John were working with the car engine running in a closed garage, they must be suffering from carbon monoxide poisoning.
Carbon monoxide (CO) is a highly toxic gas produced when fuels burn incompletely from automobile engines.
Because of strong affinity of haemoglobin with carbon monoxide, it readily combines with carbon monoxide to from a stable compound, carboxyhaemoglobin. Thus, less haemoglobin is available for oxygen transport depriving the cells of oxygen.
Exposure to carbon monoxide can usually leads to throbbing headache, drowsiness, breathlessness and often person gets fainted. In extreme cases carbon monoxide poisoning usually leads to unconsciousness, convulsions, cardiovascular failure, coma and eventually death.

The breathless persons can be treated by following method:

Oxygen treatment : The best way to treat carbon monoxide poisoning is to breathe in pure oxygen (high-dose oxygen treatment)
Oxygen chamber : Doctor may temporarily place her in a pressurized oxygen chamber (also known as a hyperbaric oxygen chamber)

Question 2.
Shreyas went to a garden on a wintry morning. When he came back, he found it difficult to breath and stated wheezing. What could be the possible condition and how can he be treated?
Answer:
(1) It indicates that Shreyas might be suffering from allergic reactions. He may have come in contact with allergens such as pollen, dust, pet dander or other environmental substances on his way in the garden. Or Shreyas may be already a patient of Asthma and his symptoms may have aggrevated due to wintry climate.

(2) If a person is allergic to a substance, such as pollen, his immune system reacts to the substance as if it was foreign and harmful, and tries to destroy it.

(3) The body reacts to these allergens by making and releasing substances known as IgE antibodies. These IgE antibodies attach to most cells in the body which release histamine. Histamine is the main substance responsible for pollen allergy symptoms such as difficulty in breathing, wheezing, sneezing, itchy throat, etc.

(4) Treatment : There are several drugs to treat the allergic reactions:

Antihistamines such as cetirizine or diphenhydramine.
Decongestants, such as pseudoephedrine or oxymetazoline.
Medications that combine an antihistamine and decongestant such as Actifed and Claritin-D.

Question 3.
Why can you feel a pulse when you keep a finger on the wrist or neck but not when you keep them on a vein?
Answer:
(1) When the heart contracts, it creates pressure that pushes blood out of heart. This pressure acts like a wave. This “wave” of pressure is the pulse you feel. But this pressure is not constant.

(2) When the heart pumps the blood out of it at the time of systole, there is maximum pressure in the arteries. This pressure weakens considerably when it reaches capillaries, and so the veins which are away from the heart are under less pressure. Due to low pressure veins have valves to prevent backflow of blood.

(3) The pressure in the arteries can be felt every time the heart beats, especially in arteries which come to surface of the body like that of the wrist and neck but not in veins.

(4) The pressure in veins is always weaker than in arteries, resulting in a weaker pulse to the point that it is undetectable by touch
alone.

(5) Owing to this, when we keep finger on the arteries of wrist or neck, we feel a pulse but not when we keep it on a vein.

Question 4.
A man’s pulse rate is 68 and cardiac output is 5500 cm3. Find the stroke volume.
Answer:
Cardiac output is the volume of blood pumped out per min for a normal adult human being it is calculated as follows:
Cardiac output = Heart rate × Stroke volume
Given : Cardiac output = 5500 cm³
Pulse rate = Heart rate = 68
By using these values stroke volume of is calculated as follows:
∴ Cardiac output = Heart rate × Stroke volume
∴ Stroke volume = Cardiac output/Heart rate
= 5500/68
= Approx. 80. ∴ Stroke volume is 80 ml.

Question 5.
Which blood vessel leaving from the heart will have the maximum content of oxygen and why?
Answer:

The Aorta leaving the heart from left ventricle carry the maximum content of oxygen.
Deoxygenated blood becomes oxygenated in the pulmonary capillaries surrounding the alveoli of lungs. The oxygenated blood from lungs is collected by the four pulmonary veins.
These pulmonary veins carry that oxygenated blood to left atrium of heart. During atrial systole that blood is carried to left ventricle.
Left ventricle then pumps that oxygenated blood to Aorta during ventricular systole. Therefore, aorta has the maximum content of oxygen.

Question 6.
If the duration of the atrial ‘systole is 0.1 second and that of complete diastole is 0.4 second, then how does one cardiac cycle complete in 0.8 second?
Answer:

The time duration required to complete one cardiac cycle is 0.8 second.
Cardiac cycle is divided into three important phases, viz, atrial systole, ventricular systole and joint diastole.
Atrial systole in normal condition lasts for 0.1 second, ventricular systole follows atrial systole and lasts for 0.3 second whereas joint diastole or complete diastole lasts for about 0.4 second.
In this way one cardiac cycle is completed in 0.8 second.

Question 7.
How is blood kept moving in the large veins of the legs?
Answer:
1. When heart undergoes systole, it pushes the blood with pressure in aorta. This pressure moves the entire circulation of the blood throughout the body. Aorta gives rise to dorsal aorta after supplying to upper parts of body. Then it divides into two arteries which enter two legs. The blood is forced to move in the legs due to blood pressure and also aided by gravity.

2. In addition, the muscles in legs help transport blood back to our heart. As the muscles of our body contract and relax to move our limbs, they squeeze the blood in veins and the blood is then pushed towards the heart.

3. The veins in legs also have valves to keep this process going and prevent blood from flowing back down towards the feet.

4. In this way blood is kept moving in the large veins of the legs.

Question 8.
Describe histological structure of artery, vein and capillary.

Answer:
Histological structure of artery and vein.

Artery is a thick walled blood vessel that carries oxygenated blood. (Exception is pulmonary artery which carries deoxygenated blood from heart to lungs for oxygenation.)
All the arteries arise from heart and carry blood away from the heart.
Each artery is made up of three layers, viz. tunica externa, tunica media and tunica interna.
Tunica externa or adventitia is the thickest layer of all. It is the outermost coat made up of connective tissue with elastic and collagen fibres.
Tunica media is the middle coat made up of smooth muscle fibres and elastic fibres. It withstands high blood pressure during ventricular systole. It is also thick.
Tunica interna or intima is the innermost coat made of endothelium and elastic layer.

Histology of Capillaries:

Capillaries are the smallest and thinnest blood vessels. Capillaries are formed by the division and re-division of the arterioles.
The wall of the capillary is made up of endothelium or squamous epithelium.
The capillary wall is permeable to water and dissolved substances.
Exchange of respiratory gases, nutrients, excretory products, etc. takes place through the capillary wall.
Capillaries unite to form venules.

Question 9.
What is blood pressure? How is it measured? Explain factors affecting blood pressure.
Answer:
1. Blood pressure:

The pressure exerted by blood on the wall of the blood vessels is called blood pressure. Pressure exerted by blood on the wall of arterial wall is arterial blood pressure. Blood pressure is described in two terms viz. systolic blood pressure and diastolic blood pressure.
Systolic blood pressure is the pressure exerted on arterial wall during ventricular contraction (systole). For a normal healthy adult the average value is 120 mmHg.
Diastolic blood pressure is the pressure on arterial wall during ventricular relaxation (diastole). For a normal healthy adult it is 80 mmHg.
B. E = SP/DP = 120/80 mmHg. Blood pressure is normally written as 120/80 mmHg. Difference between systolic and diastolic pressure is called pulse pressure normally, it is 40 mmHg.

2. Measurement of blood pressure:

Blood pressure is measured with the help of an instrument called sphygmomanometer.
The instrument consists of inflatable rubber bag cuff covered by a cotton cloth. It is connected with the help of tubes to a mercury manometer on one side and a rubber bulb on the other side.
During measurement, the person is asked to lie in a sleeping position. The instrument is placed at the level of heart and the cuff is tightly wrapped around upper arm.
The cuff is inflated till the brachial artery is blocked due to external pressure. Then pressure in the cuff is slowly lowered till the first pulsatile sound is produced. At this moment, pressure indicated in manometer is systolic pressure. Sounds heard during this measurement of blood pressure are called as Korotkoff sounds.
Pressure in the cuff is further lowered till any pulsatile sound cannot be heard due to smooth blood flow. At this moment, pressure indicated in manometer is diastolic pressure an optimal blood pressure (normal) level reads 120/80 mmHg.

3. Factors affecting blood pressure:

Cardiac output : Normal cardiac output is 5 lit/min. Increase in cardiac output increases systolic pressure.
Peripheral resistance : Peripheral resistance depends upon the diameter of blood vessels. Decrease in diameter of arterioles and capillaries under the effect of vasopressin cause increase in peripheral resistance and thereby increase in blood pressure.
Blood volume : Loss of blood in accidents decreases blood volume and thus cause decrease in blood pressure.
Viscosity of blood : Blood pressure is directly proportional to viscosity of blood.
Age : Blood pressure increases with age due to increase in inelasticity of blood vessels.
Venous return : Amount of blood brought to the heart via the veins per unit time is called the venous return and it is directly proportional to blood pressure.
Length and diameter of blood vessels : Blood pressure is directly proportional to the total length of the blood vessel. Blood pressure can also be affected by vasoconstriction or vasodilation.
Gender : Females have slightly lower BP than males of her age before menopause. However, the risk of high B. P increases in the females after menopause sets in.

Question 10.
Describe human blood and give its functions.
Answer:
Blood Composition:

Blood is a red coloured fluid connective tissue derived from embryonic mesoderm.
It has two components – the fluid plasma (55%) and the formed elements i.e. blood cells (44%).
Plasma is a straw coloured, slightly alkaline and viscous fluid having 90% water and 10% solutes such as proteins, nutrients, nitrogenous wastes, salts, hormones, etc.
Blood corpuscles are of three types, viz. erythrocytes (RBCs), white blood corpuscles (WBCs) and thrombocytes (platelets).

(5) Red blood corpuscles or Erythrocytes:

Erythrocytes or red blood corpuscles. They are circular, biconcave, enucleated cells.
The RBC size : 7 pm in diameter and 2.5 pm in thickness.
The RBC count : 5.1 to 5.8 million RBCs/ cu mm of blood in an adult male and 4.3 to 5.2 million/cu mm in an adult female.
The average life span of RBC : 120 days.
RBCs are formed by the process of erythropoiesis. In foetus, RBC formation takes place in liver and spleen whereas in adults it occurs in red bone marrow.
The old and worn out RBCs are destroyed in liver and spleen.
Polycythemia is an increase in number of RBCs while erythrocytopenia is decrease in their (RBCs) number.

Functions of RBCs:

Transport of oxygen from lungs to tissues and carbon dioxide from tissues to lungs with the help of haemoglobin.
Maintenance of blood pH as haemoglobin acts as a buffer.
Maintenance of the viscosity of blood.

(6) White blood corpuscles / Leucocytes:

1. Leucocytes or White Blood Corpuscles (WBCs) are colourless, nucleated, amoeboid and phagocytic cells.

2. Their size ranges between 8 to 15 pm. Total WBC count is 5000 to 9000 WBCs/cu mm of blood. The average life span of a WBC is about 3 to 4 days.

3. They are formed by leucopoiesis in red bone marrow, spleen, lymph nodes, tonsils, thymus and Payer’s patches, whereas the dead WBCs are destroyed by phagocytosis in blood, liver and lymph nodes.

4. Leucocytes are mainly divided into two types, viz., granulocytes and agranulocytes.

5. Granulocytes : Granulocytes are cells with granular cytoplasm and lobed nucleus. Based on their staining properties and shape of nucleus, they are of three types, viz. neutrophils, eosinophils and basophils.

(I) Neutrophils:

In neutrophils, the cytoplasmic granules take up neutral stains.
Their nucleus is three to five lobed.
It may undergo changes in structure hence they are called polymorphonuclear leucocytes or polymorphs.
Neutrophils are about 70% of total WBCs.
They are phagocytic in function and engulf microorganisms.

(II) Eosinophils or acidophils:

Cytoplasmic granules of eosinophils take up acidic dyes such as eosin. They have bilobed nucleus.
Eosinophils are about 3% of total WBCs.
They are non-phagocytic in nature.
Their number increases (i.e. eosinophilia) during allergic conditions.
They have antihistamine property.

(III) Basophils:

The cytoplasmic granules of basophils take up basic stains such as methylene blue.
They have twisted nucleus.
In size, they are smallest and constitute about 0.5% of total WBCs.
They too are non-phagocytic.
Their function is to release heparin which acts as an anticoagulant and histamine that is involved in inflammatory and allergic reaction.

6. Agranulocytes : There are two types of agranulocytes, viz. monocytes and lymphocytes. Agranulocytes do not show cytoplasmic granules and their nucleus is not lobed. They are of two types, viz. lymphocytes and monocytes.
(I) Lymphocytes:

Agranulocytes with a large round nucleus are called lymphocyte.
They are about 30% of total WBCs.
Agranulocytes are responsible for immune response of the body by producing antibodies.

(II) Monocytes:

Largest of all WBCs having large kidney shaped nucleus are monocytes. They are about 5% of total WBCs.
They are phagocytic in function.
They can differentiate into macrophages for engulfing microorganisms and removing cell debris. Hence they are also called scavengers.
At the site of infections they are seen in more enlarged form.

(7) Thrombocytes/Platelets:

Thrombocytes or platelets are non- nucleated, round and biconvex blood corpuscles.
They are smallest corpuscles measuring about 2.5 to 5 mm in diameter with a count of about 2.5 lakhs/cu mm of blood.
Their life span is about 5 to 10 days.
Thrombocytes are formed from megakaryocytes of bone marrow. They break from these cells as fragments during the process of thrombopoiesis.
Thrombocytosis is the increase in platelet count while thrombocytopenia is decrease in platelet count.
Thrombocytes possess thromboplastin which helps in clotting of blood.
Therefore, at the site of injury platelets aggregate and form a platelet plug. Here they release thromboplastin due to which further blood clotting reactions take place.

(8) Functions of blood:

Transport of oxygen and carbon dioxide
Transport of food
Transport of waste product
Transport of hormones
Maintenance of pH
Water balance
Transport of heat
Defence against infection
Temperature regulation
Blood clotting/coagulation
Helps in healing

12th Std Biology Questions And Answers:

12th Biology Chapter 9 Exercise Control and Co-ordination Solutions Maharashtra Board

January 8, 2025January 7, 2025 by Prasanna

Balbharti Maharashtra State Board 12th Biology Textbook Solutions Chapter 9 Control and Co-ordination Textbook Exercise Questions and Answers.

Control and Co-ordination Class 12 Exercise Question Answers Solutions Maharashtra Board

Class 12 Biology Chapter 9 Exercise Solutions Maharashtra Board

Biology Class 12 Chapter 9 Exercise Solutions

1. Multiple choice questions

Question 1.
The nervous system of mammals uses both electrical and chemical means to send signals via neurons. Which part of the neuron receives impulse?
(a) Axon
(b) Dendron
(c) Nodes of Ranvier
(d) Neurilemma
Answer:
(b) Dendron

Question 2.
……………. is a neurotransmitter.
(a) ADH
(b) Acetyl CoA
(c) Acetyl choline
(d) Inositol
Answer:
(c) Acetyl choline

Question 3.
The supporting cells that produce myelin sheath in the PNS are …………….
(a) Oligodendrocytes
(b) Satellite cells
(c) Astrocytes
(d) Schwann cells
Answer:
(d) Schwann cells

Question 4.
A collection of neuron cell bodies located outside the CNS is called …………….
(a) tract
(b) nucleus
(c) nerve
(d) ganglion
Answer:
(d) ganglion

Question 5.
Receptors for protein hormones are located …………….
(a) in cytoplasm
(b) on cell surface
(c) in nucleus
(d) on Golgi complex
Answer:
(b) on cell surface

Question 6.
If parathyroid gland of man Eire removed, the specific result will be …………….
(a) onset of aging
(b) disturbance of Ca⁺⁺
(c) onset of myxoedema
(d) elevation of blood pressure
Answer:
(b) disturbance of Ca⁺⁺

Question 7.
Hormone thyroxine, adrenaline and non¬adrenaline are formed from ……………
(a) Glycine
(b) Arginine
(c) Ornithine
(d) Tyrosine
Answer:
(d) Tyrosine

Question 8.
Pheromones are chemical messengers produced by animals and released outside the body. The odour of these substance affects …………….
(a) skin colour
(b) excretion
(c) digestion
(d) behaviour
Answer:
(d) behaviour

Question 9.
Which one of the following is a set of discrete endocrine gland?
(a) Salivary glands, thyroid, adrenal, ovary
(b) Adrenal, testis, ovary, liver
(c) Pituitary, thyroid, adrenal, thymus
(d) Pituitary, pancreas, adrenal, thymus
Answer:
(c) Pituitary, thyroid, adrenal, thymus

Question 10.
After ovulation, Graafian follicle changes into …………….
(a) corpus luteum
(b) corpus albicans
(c) corpus spongiosum
(d) corpus callosum
Answer:
(a) corpus luteum

Question 11.
Which one of the following pairs correctly matches a hormone with a disease resulting from its deficiency?
(a) Parathyroid hormone – Diabetes insipidus
(b) Luteinising hormone – Diabetes mellitus
(c) Insulin – Hyperglycaemia
(d) Thyroxine – Tetany
Answer:
(c) Insulin – Hyperglycaemia

Question 12.
……………. is in direct contact of brain in humans.
(a) Cranium
(b) Dura mater
(c) Arachnoid
(d) Pia mater
Answer:
(d) Pia mater

2. Very very short answer questions.

Question 1.
What is the function of red nucleus?
Answer:
Red nucleus plays an important role in controlling posture and muscle tone, modifying some motor activities and motor coordination.

Question 2.
What is the importance of corpora quadrigemina?
Answer:
Corpora quadrigemina consists of 4 solid rounded structures, viz. superior and inferior colliculi. Superior colliculi control visual reflexes while inferior colliculi control auditory reflexes.

Question 3.
What does the cerebellum of brain control?
Answer:
Cerebellum of brain is an important centre which maintains equilibrium of body, posture, balancing orientation, moderation of voluntary movements and maintenance of muscle tone.

Question 4.
Name the three ear ossicles.
Answer:
Malleus [hammer], incus [anvil] and stapes [stirrup].

Question 5.
Name the anti abortion hormone.
Answer:
Progesterone.

Question 6.
Name an organ which acts as temporary endocrine gland.
Answer:
Placenta. Corpus luteum in ovary.

Question 7.
Name the type of hormones which bind to the DNA and alter the gene expression.
Answer:
Steroid hormones.

Question 8.
What is the cause of abnormal elongation of long bones of arms and legs and of lower jaw.
Answer:
Hypersecretion of growth hormones in adults causes abnormal elongation of long bones of arms and legs and of lower jaw i.e. acromegaly.

Question 9.
Name the hormone secreted by the pineal gland.
Answer:
Melatonin.

Question 10.
Which endocrine gland plays important, role in improving immunity?
Answer:
The endocrine gland, thymus plays an important role in improving immunity.

3. Match the organism with the type of nervous system found in them.

Column A	Column B
(1) Neurons	(a) Earthworm
(2) Ladder type	(b) Hydra
(3) Ganglion	(c) Flatworm
(4) Nerve net	(d) Human

Answer:

Column A	Column B
(1) Neurons	(d) Human
(2) Ladder type	(c) Flatworm
(3) Ganglion	(a) Earthworm
(4) Nerve net	(b) Hydra

4. Very short answer questions.

Question 1.
Describe the endocrine role of islets of Langerhans.
OR
Islets of Langerhans.
Answer:
Endocrine cells of pancreas form groups of cells called Islets of Langerhans. There are four kinds of cells in islets of Langerhans which secrete hormones.

Alpha (α) cells : They are 20% and secrete glucagon. Glucagon is a hyperglycemic hormone. It stimulates liver for glucogenolysis and increases the blood glucose level.
Beta (β) cells : They are 70% and secrete insulin. Insulin is a hypoglycemic hormone. It stimulates liver and muscles for glycogenesis. This lowers blood glucose level.
Delta (δ) cells : They are 5% and secrete somatostatin. Somatostatin inhibits the secretion of glucagon and insulin. It also decreases the gastric secretions, motility and absorption in digestive tract. In general it is a growth inhibiting factor.
PP cells or F cells : They form 5%. They secrete pancreatic polypeptide (PP) which inhibits the release of pancreatic juice.

Question 2.
Mention the function of testosterone?
Answer:
Testosterone is a steroid sex hormone secreted by testes and cortex of adrenal glands. It controls the secondary sexual characters in males.

Question 3.
Give symptoms of the disease caused by hyposecretion of ADH.
Answer:
Polydipsia, i.e. frequent thirst and polyuria, i.e. frequent urination are the symptoms of the disease caused by hyposecretion of ADH.

5. Short answer questions

Question 1.
Rakesh got hurt on his head when he fell down from his motorbike. Which inner membranes must have protected his brain? What other roles do they have to play
Answer:

When Rakesh fell down from his motorbike, the inner membranes that protected his brain were meninges, viz. dura mater, arachnoid membrane and pia mater. Morevover, CSF must have also acted as a shock absorber.
Dura mater : It is the outer tough membrane protective in function.
Arachnoid membrane : It is the middle web-like membrane which communicates with fluids of upper sub dural space and lower sub arachnoid space.
Pia mater : It is the innermost highly vascularised nutritive membrane in close contact with brain and spinal cord.

Question 2.
Injury to medulla oblongata may prove fatal.
OR
Injury to medulla oblongata causes sudden death. Explain.
Answer:

Medulla oblongata is the region of the brain that controls all the involuntary activities.
Vital activities such as heartbeats, respiration, vasomotor activities, peristalsis, etc. are under the control of medulla oblongata.
When medulla oblongata is injured, all these vital functions are instantly stopped.
Therefore, injury to medulla oblongata causes sudden death.

Question 3.
Distinguish between the sympathetic and parasympathetic nervous system on the basis of the effect they have on:
Heartbeat andUrinary Bladder.
Answer:

Sympathetic Nervous System	Parasympathetic	Nervous System
(1) Heartbeat	Increases	Decreases
(2) Urinary bladder	Relaxes and stores urine	Contracts causing micturition

Question 4.
While holding a tea cup Mr. Kothari’s hands rattle. Which disorder he may be suffering from and what is the reason for this?
Answer:

This condition is due to Parkinson’s disease.
It is due to degeneration of dopamine- producing neurons in the CNS.
80% of the patients develop this condition along with stiffness, difficulty in walking, balance and coordination.

Question 5.
List the properties of the nerve fibres.
Answer:

Excitability / irritability
Conductivity
Stimulus
Summation
All or none
Refractory period
Synaptic delay
Synaptic fatigue
Velocity.

Question 6.
How does tongue detect the sensation of taste?
Answer:

The surface of tongue is with gustatoreceptors.
These receptors are sensitive to the chemicals [sweet, salt, sour, bitter and umami (savory)] present in the food.
The receptor cells get stimulated, generate the impulse which is given to the sensory neuron.

Question 7.
State the site of production and function of Secretin, Gastrin and Cholecystokinin.
Answer:

Hormone	Site of production	Functions
1. Secretin	Duodenal mucosa	Stimulates secretion of pancreatic juice and bile from pancreas and liver respectively.
2. Gastrin	Gastric mucosa	Stimulates gastric glands to secrete gastric juice.
3. Cholecystokinin	Duodenal mucosa	Stimulates pancreas and gall bladder to release pancreatic enzymes and bile respectively.

Question 8.
An adult patient suffers from low heart rate, low metabolic rate and low body temperature. He also lacks alertness, intelligence and initiative. What can be this disease? What can be its cause and cure ?
Answer:

The above symptoms indicate that the person is suffering from Myxoedema.
Myxoedema is condition caused due to hypothyroidism.
Hypothyroidism causes deficiency of thyroid hormones like T₃ and T₄ (thyroxine). This results in low BMR.
This condition can be cured by giving injections of thyroxine or tablets containing hormone preparation.

Question 9.
Where is the pituitary gland located? Enlist the hormones secreted by anterior pituitary.
Answer:
The pituitary gland is attached to hypothalamus on the ventral surface of brain. It is lodged in a bony depression called sella turcica of sphenoid bone.
For names of hormones:

GH : [Growth Hormone/STH : Somatotropic Hormone]
TSH/TTH – [Thyroid Stimulating Hormone/ Thyrotropic Hormone]
ACTH – [adrenocorticotropic hormone]
PRL – [prolactin]

Gonadotropins-

FSH [follicle stimulating hormone]
LH/ICSH – [leutinizing hormone/ interstitial cells stimulating hormone]

Question 10.
Explain how the adrenal medulla and sympathetic nervous system function as a closely integrated system.
Answer:

Adrenal medulla originates from embryonic neuro – ectoderm.
It consists of rounded group of large granular cells called chromaffin cells. They are modified post-ganglionic cells of sympathetic nervous system which have lost normal processes and acquired glandular function.
These cells are connected with pre-ganglionic fibres of sympathetic nervous system.
Hence adrenal medulla is an extension of sympathetic nervous system.
Thus adrenal medulla and sympathetic nervous system functions as a closely integrated system.

Question 11.
Name the secretion of alpha, beta and delta cells of islets of Langerhans. Explain their role.
Answer:

Pancreatic islet cells	Secretion	Functions
1. Alpha cells	Glucagon	Stimulates glycogenolysis in the liver
2. Beta cells	Insulin	Stimulates glycogenesis in the liver and muscles
3. Delta cells	Somatostatin	Inhibits the secretion of glucagon and insulin. It also decreases the gastric secretions, motility and absorption in digestive tract.

Question 12.
Which are the two types of goitre? What are their causes?
Answer:
(1) Goitre is the enlargement of thyroid gland. It is easily visible at the base of neck when a person is suffering from it.

(2) Goitre is of two types.

Simple goitre : It is also called endemic goitre. This is due to iodine deficiency in the food. This causes iodine deficit in blood. In an attempt to take more iodine from blood, the blood supply to the gland increases. This results in swelling on the thyroid.
Exophthalmic goitre : It is also called toxic goitre. This is due to hyperactive thyroid gland. This can happen if there is overstimulation of thyroid due to excess of ACTH. This disorder is also called Grave’s disease or hyperthyroidism.

Question 13.
Name the ovarian hormone and give their functions.
Answer:

Hormone	Functions
Oestrogen	It is responsible for secondary sexual characters in female.
Progesterone	Essential for thickening of uterine endometrium, thus preparing the uterus for implantation of fertilized ovum. It is responsible for development of mammary glands during pregnancy. It inhibits uterine contractions during pregnancy.
Relaxin	It relaxes the cervix of the pregnant female and ligaments of pelvic girdle during parturition.
Inhibin	It inhibits the FSH and GnRH production.

6. Answer the following.

Complete the table.

Location	Cell type	Function
PNS	————-	Produce myelin sheath.
PNS	Satellite cells	————-
————	Oligodendrocytes	Form myelin sheath around central axon.
CNS	————	Pathogens are destroyed by phagocytosis. (Phagocytose)
CNS	————	Form the epithelial lining of brain cavities and central canal.

Answer:

Location	Cell type	Function
PNS	Schwann cells	Produce myelin sheath.
PNS	Satellite cells	Supply nutrients to surrounding neurons, protect and cushion nearby neurons.
CNS	Oligodendrocytes	Form myelin sheath around central axon.
CNS	Microglia	Pathogens are destroyed by phagocytosis. (Phagocytose)
CNS	Ependyma	Form the epithelial lining of brain cavities and central canal.

7. Long answer questions.

Question 1.
Explain the process of conduction of nerve impulses up to development of action potential.
Answer:

The origin and maintenance of resting potential depends on the original state of no stimulation.
Any stimulus or disturbance to the membrane will make the membrane permeable to Na⁺ ions. This causes rapid influx of Na⁺ ions.
The voltage gated Na⁺/K⁺ channels are unique. They can change the potential difference of the membrane as per the stimulus received and also the gates operate separately and are self closing.
During resting potential, both gates are closed and resting potential is maintained.
However during depolarization, the Na⁺ channels open but not the K⁺ channels. This causes Na⁺ to rush into the axon and bring about a depolarisation. This condition is called action potential.
Extra cellular fluid (ECF) becomes electronegative with respect to the inner membrane which becomes electropositive.

Question 2.
Draw the neat labelled diagrams.
a. Human ear.
Answer:

b. Sectional view of human eye.
Answer:

c. Draw the neat labelled diagram of sagittal section or L.S. of human brain
Answer:

d. Draw the neat labelled diagram of Multipolar Neuron.
Answer:

Question 3.
Answer the questions after observing the diagram given below.

a. What do the synaptic vesicles contain?
Answer:
Synaptic vesicles contain a neurotransmitter – acetyl choline.

b. What process is used to release the neurotransmitter ?
Answer:
Exocytosis.

c. What should be the reason for the next impulse to be conducted?
Answer:
Removal of neurotransmitter by the action of acetyl cholinesterase.

d. Will the impulse be carried by post synaptic membrane even if one pre-synaptic neuron is there?
Answer:
As far as impulse is transmitted by pre-synaptic neuron, it will be received by post-synaptic neuron.

e. Can you name the channel responsible for their transmission?
Answer:
Ca⁺⁺ channel

Question 4.
Explain the Reflex Pathway with the help of a neat labelled diagram.
OR
With the help of a neat and labelled diagram, describe reflex arc.
Answer:

I. Reflex action : Reflex action Is defined as a quick, automatic involuntary and often unconscious action brought about when the receptors are stimulated by external or internal stimuli.

II. Reflex arc : Reflex actions are controlled by CNS. Reflex arc is the structural or functional unit of reflex action. Simple reflex arc is formed of the following five components.
(1) Receptor organ : The sensory part that receives the stimulus is called receptor organ. It can be any sense organ that receives the stimulus and converts it into the impulse, e.g. skin, eye, ear, tongue, nasal epithelium, etc.

(2) Sensory neuron or afferent neuron:
Sensory part carrying impulse from receptor organ to CNS is called sensory neuron. Its cyton is located in dorsal root ganglion. Its dendron is long and connected to receptor while the axon enters in the grey matter of spinal cord to form a synapse.

(3) Association, adjustor or intermediate neuron : It is present in the grey matter of spinal cord. Receiving impulse from sensory neuron, interpreting it and generating motor impulse are done by association neuron.
(4) Motor neuron (effector) : The cyton of motor neuron is present in the ventral horn of grey matter and axon travels through ventral root. It conducts motor impulse from spinal cord to effector organ.

(5) Effector organ : Effector organ is a specialized part of the body which is excited by receiving the motor impulse. It gives proper response to the stimulus, e.g. muscles or glands. The path of reflex action is followed by the unidirectional impulse. It originates in the receptor organ and ends in effector organ through CNS.

Question 5.
Krishna was going to school and on the way he saw a major bus accident. His heartbeat increased and hands and feet become cold. Name the part of the nervous system that had a role to play in this reaction.
Answer:

The symptoms observed in Krishna were due to sympathetic nervous system. Emergency conditions trigger sympathetic nervous system to stimulate adrenal medulla.
The cells of adrenal medulla secrete catecholamines like adrenaline and nor¬adrenaline.
These hormones have direct effect on the pacemaker of the heart which causes increase in the heart rate and other associated symptoms.
This is a typical fright reaction caused by intervention of sympathetic nervous system.

Question 6.
What will be the effect of thyroid gland atrophy on the human body?
Answer:

Atrophy means degeneration. Atrophy of thyroid gland will result in deficient secretion of thyroid hormones leading to hypothyroidism. Deficiency of thyroid hormones [T₃ and T₄] and thyrocalcitonin will cause following effects on the body.
Decrease in BMR i.e. basal metabolic rate, decrease in the blood pressure, heart beat, body temperature, etc.
Occurrence of myxoedema in which there is abnormal deposition of fats under the skin giving puffy appearance in adults.
Irregularities in menstrual cycle in case of female patients.
Hair become brittle and fall.
Calcium metabolism also disturbs due to lack of thyrocalcitonin.

Question 7.
Write the names of hormones and the glands secreting them for the regulation of following functions
(a) Growth of thyroid and secretion of thyroxine.
Answer:
TSH by adenohypophysis.

(b) Helps in relaxing pubic ligaments to facilitate easy birth of young ones.
Answer:
Relaxin by degenerating corpus luteum of the ovary.

(d) Controls calcium level in the blood.
Answer:
Calcitonin [hypocalcemic hormone] by thyroid and parathormone [ hypercalcemic hormone] by parathyroid glands.

(e) Controls tubular absorption of water in kidneys.
Answer:
ADH by hypothalamus.

(f) Urinary elimination of water.
Answer:
Atrial natriuretic factor by atria of heart.

(g) Sodium and potassium ion metabolism.
Answer:
Aldosterone by adrenal cortex.

(h) Basal Metabolic rate.
Answer:
T₃ and T₄ by thyroid gland.

(I) Uterine contraction.
Answer:
Oxytocin by hypothalamus.

(j) Heartbeat and blood pressure.
Answer:
Adrenaline, non-adrenaline [stimulation] and acetylcholine [inhibition] by adrenal medulla.

(k) Secretion of growth hormone.
Answer:
GHRF by hypothalamus.

(l) Maturation of Graafian follicle.
Answer:
FSH by anterior pituitary.

Question 8.
Explain the role of hypothalamus and pituitary as a coordinated unit in maintaining homeostasis.
Answer:

Homeostasis is maintenance of constant internal environment of the body.
When certain hormones from any endocrine glands are secreted in excess quantity, the : inhibiting factors from hypothalamus, automatically exert negative feedback and stop the production of stimulating hormones from pituitary.
Similarly, if any hormone is in deficit, then j the concerned gland is given message through releasing factor. This way the hormone production remains in a balanced state or homeostasis.
E.g. If thyroxine from thyroid gland is secreted in excess, the secretion of TSH from pituitary is stopped by stopping the production of TRF from hypothalamus.
Though most of the endocrine glands are under the influence of pituitary gland, it is in turn controlled by hypothalamus.
Hypothalamus secretes releasing factors and inhibiting factors and hence regulate the secretions of pituitary (hypophysis).
There is negative feedback mechanism in controlling the secretions of the endocrine glands.
Hypothalamus forms the hypothalamo- hypophyseal axis through which transportation of neurohormones take place.

Following are the releasing and inhibiting factors produced by hypothalamus:

Somatotropin/GHRF : It stimulates release of growth hormone.
Somatostatin/GHRIF : It inhibits the release of growth hormone.
Adrenocorticotropin Releasing Hormone / CRF : It stimulates the release of ACTH by the anterior pituitary gland.
Thyrotropin Releasing Hormone /TRF : It stimulates the release of TSH by anterior pituitary gland.
Gonadotropin Releasing Hormone (GnRH) : It stimulates pituitary to secrete gonadotropins.
Prolactin Inhibiting Hormone (Prolactostatin) : It inhibits prolactin released by anterior pituitary gland.
Gastrin Releasing Peptide (GRP).
Gastric Inhibitory Polypeptide (GIP).

Question 9.
What is adenohypophysis ? Name the hormones secreted by it.
Answer:

Adenohypophysis is the large anterior lobe of pituitary gland.
It is derived from embryonic ectoderm in the form of Rathke’s pouch which is a small outgrowth from the roof of embryonic stomodaeum.
It is made up of epitheloid secretory cells.

It secretes following hormones:

GH : [Growth Hormone/STH : Somatotropic Hormone]
TSH/TTH – [Thyroid Stimulating Hormone/ Thyrotropic Hormone]
ACTH – [adrenocorticotropic hormone]
PRL – [prolactin]

Gonadotropins-

FSH [follicle stimulating hormone]
LH/ICSH – [leutinizing hormone/ interstitial cells stimulating hormone]

Question 10.
Describe, in brief, an account of disorders of adrenal gland.
Answer:
(1) Disorders of adrenal cortical secretions are caused due to hyposecretion and hypersecretion of adrenal corcoid hormones.

(2) Hyposecretion of corticosteroids causes Addison’s disease.

(3) The symptoms of Addison’s disease are low blood sugar, low body temperature, feeble heart action, low BR acidosis, low Na⁺ and K⁺ concentration in plasma, excessive loss of Na⁺ and water in urine, impaired kidney functioning and kidney failure, etc. it leads to weight loss, general weakness, nausea, vomiting and diarrhoea.

(4) Hypersecretion of corticoids causes Cushing’s disease.

(5) The symptoms of Cushing’s disease are high blood sugar level, glucosuria, alkalosis, enhancement of total quantity of electrolytes in extracellular fluid, polydipsia, increased BR muscle paralysis, obesity, wasting of limb muscles, etc.

Question 11.
Explain action of steroid hormones and proteinous hormones.
OR
Explain the mode of action of steroid hormones.
Answer:
The hormones always act on their target organs or tissues to induce their effects. The target tissues have specific binding sites or receptor sites which contain hormone receptors.
I. Steroid hormones:

The steroid hormones are lipid soluble and can easily cross the lipoproteinous plasma membrane.
The hormone receptors for steroid hormones are present in cytoplasm or in nucleus.
Hormone-receptor complex formed in cytoplasm enters the nucleus and regulate the gene expression or chromosome function.
In some cases the receptors are present inside the nucleus where hormone receptor complex is formed.
These complexes interact with the genome to evoke biochemical changes that result in physiological and developmental functions.

II. Protein hormones:

The hormone receptors for protein hormones are present on the cell membrane (i.e. membrane bound receptors).
When the hormone binds to its receptor, it forms hormone-receptor complex. Each receptor is specific to a specific hormone.
The hormones which interact with membrane bound receptors normally do not enter the target cell but generate second messengers. Such as cyclic AMP Ca⁺⁺ or IP (Inositol triphosphate), etc.
This leads to certain biochemical changes : in the target tissue.
Thus, the tissue metabolism and consequently the physiological functions are regulated by hormones.

Question 12.
Describe in brief an account of disorders of the thyroid.
OR
What are the functional disorders of thyroid gland? Describe in brief.
Answer:
Disorders of thyroid gland are of three types, viz. hypothyroidism, hyperthyroidism and simple goitre.
(1) Hypothyroidism : Hypothyroidism is deficient secretion of thyroxine. This hyposecretion causes two types of disorders, viz. cretinism in children and myoxedema in adults.
(i) Cretinism : Hyposecretion of thyroxine in childhood causes cretinism. The symptoms of cretinism are retardation of physical and mental growth.

(ii) Myxoedema : Deficiency of thyroxine in adults causes this disorder. It is also referred to as Gull’s disease. Symptoms are thickening and puffiness of the skin and subcutaneous tissue particularly of face and extremities. Patients with low BMR. It also causes mental dullness, loss of memory, slow action.

(2) Hyperthyroidism : Excessive secretion of thyroxine causes exophthalmic goitre or Grave’s disease. There is slight enlargement of thyroid gland. It increases BMR, heart rate, pulse rate and BE Reduction in body weight due to rapid oxidation, nervousness, irritability. Peculiar symptom is exophthalmos, i.e. bulging of eyeballs with staring look and less blinking. This is caused by deposition of fats behind the eye balls in eye sockets. There is muscular weakness and loss of weight.

(3) Simple goitre (Iodine deficiency goitre) : Simple goitre occurs due to deficiency of iodine in diet or drinking water. Simple goitre causes enlargement of thyroid gland. Thyroid gland in an attempt to get more iodine from the blood, swells due to increased blood supply. Prevention of goitre can be done by administering iodized table salt. It is also called endemic goitre as it is common in hilly areas.

12th Std Biology Questions And Answers:

12th Chemistry Chapter 6 Exercise Chemical Kinetics Solutions Maharashtra Board

January 8, 2025January 7, 2025 by Bhagya

Balbharti Maharashtra State Board 12th Chemistry Textbook Solutions Chapter 6 Chemical Kinetics Textbook Exercise Questions and Answers.

Chemical Kinetics Class 12 Exercise Question Answers Solutions Maharashtra Board

Class 12 Chemistry Chapter 6 Exercise Solutions Maharashtra Board

Chemistry Class 12 Chapter 6 Exercise Solutions

1. Choose the most correct option.

Question i.
The rate law for the reaction aA + bB → P is rate = k[A] [B]. The rate of reaction doubles if
a. concentrations of A and B are both doubled.
b. [A] is doubled and [B] is kept constant
c. [B] is doubled and [A] is halved
d. [A] is kept constant and [B] is halved.
Answer:
b. [A] is doubled and [B] is kept constant

Question ii.
The order of the reaction for which the units of rate constant are mol dm^-3 s^-1 is
a. 1
b. 3
c. 0
d. 2
Answer:
c. 0

Question iii.
The rate constant for the reaction 2N₂O₅(g) → 2N₂O₄(g) + O₂(g) is 4.98 × 10^-4 s^-1. The order of reaction is
a. 2
b. 1
c. 0
d. 3
Answer:
b. 1

Question iv.
Time required for 90 % completion of a certain first order reaction is t. The time required for 99.9 % completion will be
a. t
b. 2t
c. t/2
d. 3t
Answer:
d. 3t

Question v.
Slope of the graph ln[A]_t versus t for first order reaction is
a. -k
b. k
c. k/2. 303
d. -k/2. 303
Answer:
a. -k

Question vi.
What is the half life of a first order reaction if time required to decrease concentration of reactant from 0.8 M to 0.2 M is 12 h?
a. 12 h
b. 3 h
c. 1.5 h
d. 6 h
Answer:
d. 6 h

Question vii.
The reaction, 3ClO^3Θ ClO₃^Θ + 2 Cl^Θ occurs in two steps,
(i) 2 ClO^– → ClO₂^Θ
(ii) ClO₂^Θ + ClO^Θ → ClO₃^Θ + Cl^Θ

The reaction intermediate is
a. Cl^Θ
b. ClO₂^Θ
c. ClO₃^Θ
d. ClO^ΘAnswer:
b. ClO₂^Θ

Question viii.
The elementary reaction O₂(g) + O(g) → 2O₂(g) is
a. unimolecular and second order
b. bimolecular and first order
c. bimolecular and second order
d. unimolecular and first order
Answer:
c. bimolecular and second order

Question ix.
Rate law for the reaction, 2NO + Cl₂ → 2 NOCl is rate = k[NO₂]²[Cl₂]. Thus k would increase with
a. increase of temperature
b. increase of concentration of NO
c. increase of concentration of Cl₂
d. increase of concentrations of both Cl₂ and NO
Answer:
a. increase of temperature

Question x.
For an endothermic reaction, X ⇌ Y. If E f is activation energy of the forward reaction and Er that for reverse reaction, which of the following is correct?
a. E_f = E_r
b. E_f< E_r
c. E_f > E_r
d. ∆H = E_f – E_r is negative
Answer:
(c) Ef → Er

2. Answer the following in one or two sentences.

Question i.
For the reaction,
N₂(g) + 3 H₂(g) → 2NH₃(g), what is the relationship among \(\frac{\mathrm{d}\left[\mathrm{N}_{2}\right]}{\mathrm{dt}}\)\(\frac{\mathrm{d}\left[\mathrm{H}_{2}\right]}{\mathrm{dt}} \text { and } \frac{\mathrm{d}\left[\mathrm{NH}_{3}\right]}{\mathrm{dt}} ?\)
Answer:
N_2(g) + 3H_2(g) → 2NH_3(g)
From the above reaction, when 1 mole of N₂ reacts, 3 moles of H₂ are consumed and 2 moles of NH₃ are formed.

If the instantaneous rate R of the reaction is represented in terms of rate of the consumption of N₂then, \(R=-\frac{d\left[\mathrm{~N}_{2}\right]}{d t}\)

Hence the rate of reaction in terms of concentration changes in N₂, H₂ and NH₃ may be represented as,

Question ii.
For the reaction,
CH₃Br(aq) + OH-(aq) → CH₃OH^Θ (aq) +Br^Θ (aq), rate law is rate = k[CH₃Br][OH^Θ]
a. How does reaction rate changes if [OH^Θ] is decreased by a factor of 5?
b. What is change in rate if concentrations of both reactants are doubled?
Solution :
Given :
(a) Rate = R = k [CH₃Br] x [OH^–]
If R₁ and R₂ are initial and final rates of reaction then,

Rate will be increased 4 time.

Question iii.
What is the relationship between coeffients of reactants in a balanced equation for an overall reaction and exponents in rate law. In what case the coeffients are the exponents?
Answer:
Explanation : Consider the following reaction, aA + bB → products

If the rate of the reaction depends on the concentrations of the reactants A and B, then, by rate law,
R α [A]^a [B]^b
∴ R = k [A]^a [B^b
where [A] = concentration of A and
[B] = concentration of B

The proportionality constant k is called the velocity constant, rate constant or specific rate of the reaction.

a and b are the exponents or the powers of the concentrations of the reactants A and B respectively when observed experimentally.

The exponents or powers may not be necessarily a and b but may be different x and y depending on experimental observations. Then the rate R will be,
R = k [A]^x [B]^y
For example, if x = 1 and y = 2, then,
R = k [A] x [B]²

Question iv.
Why all collisions between reactant molecules do not lead to a chemical reaction?
Answer:
(i) Collisions of reactant molecules : The basic re-quirements of a reaction is that the reacting species (atoms, ions or molecules) must come together and collide for a reaction to occur. Therefore the rate of the reaction shall depend on the rate and frequency of collisions which increase with the amount of reacting species and temperature.

However it is observed that the rate of reaction is very low as compared to the rate of collisions between reacting species in gaseous phase or liquid phase. This suggests that all the collisions are not fruitful leading to a reaction. Hence it is necessary to consider another factor like energy of colliding species along with collision frequency.

(ii) Energy requirement (Activation energy) : The colliding molecules must possess a certain mini-mum energy called activation energy required far breaking and making bonds resulting in the reaction. This implies that the colliding molecules must have energy equal to or greater than the activation energy. The colliding molecules with less energy do not react.

(iii) Orientation of reactant molecules : The concept of activation energy is satisfactory in case of simple molecules or ions but not in case of complex or higher polyatomic molecules. It is observed that the rates of reaction are less as compared to the rates of collisions between activated molecules with activation energy.

This suggests that in addition, the colliding molecules must have proper orientations relative to each other during collisions. For example, consider the reaction, A – B-l-C → A + B – C. For the reaction to occur, C must collide with B while collisions with A will not be fruitful. Since B has to bond with C.

Question v.
What is the activation energy of a reaction?
Answer:
Activation energy : The energy required to form activated complex or transition state from the reactant molecules is called activation energy.
OR
The height of energy barrier in the energy profile diagram is called activation energy.

Question vi.
What are the units for rate constants for zero order and second order reactions if time is expressed in seconds and concentration of reactants in mol/L?
Answer:
(a) For a zero order reaction, the rate constant has units, molL^-1s^-1.
(b) For second order reaction,
Rate = k x [Reactant]²

Question vii.
Write Arrhenius equation and explain the terms involved in it.
Answer:
Arrhenius equation is represented as k = A x e^-E_a/RT
where
k = Rate constant at absolute temperature T
E_a = Energy of activation R = Gas constant
A = Frequency factor or pre-exponential factor.

Question viii.
What is the rate determining step?
Answer:
Many chemical reactions take place in a series of elementary steps. Among many steps of the reaction, one of the steps is the slowest step compared to other steps.

Rate determining step : The slowest step in the reaction mechanism which involves many steps is called the rate-determining step.

Question ix.
Write the relationships between rate constant and half life of fist order and zeroth order reactions.
Answer:
(a) For first order reaction, half-life period t_1/2 is, \(t_{1 / 2}=\frac{0.693}{k}\) where k is the rate constant.
(b) For zeroth-order reaction, half half period (t_1/2) is, \(t_{1 / 2}=\frac{[\mathrm{A}]_{0}}{2 k}\) where k is the rate constant and [A]₀ is initial concentration of the reactant.

Question x.
How do half lives of the fist order and zero order reactions change with initial concentration of reactants?
Answer:
(A) For the first order reaction, half life, t_1/2 is given by, \(t_{1 / 2}=\frac{0.693}{k}\) where k is rate constant. Hence it is independent of initial concentration of the reactant.

(B) Zero order reaction,
\(t_{1 / 2}=\frac{[\mathrm{A}]_{0}}{2 k}\) where [A]₀ is initial concentration of the reactant.

Hence, half life period increases with the increase in concentration of the reactant.

3. Answer the following in brief.

Question i.
How instantaneous rate of reaction is determined?
Answer:
(1) The instantaneous rate is expressed as an infinite¬simal change in concentration (- dc) of the reactant with the infinitesimal change in time (dt).
For a reaction, A → B, let an infinitesimal change in A be – dc in time dt, then Rate \(=\frac{d[\mathrm{~A}]}{d t}\).

Hence, it is represented as,
∴ Instantaneous rate \(=-\frac{d[\mathrm{~A}]}{d t}\)

The negative sign indicates a decrease in the concentration of A.

It is obtained by drawing a tangent to the curve obtained by plotting the concentration against the time. Hence, the slope at a given point represents the instantaneous rate of the reaction.

(2) The instantaneous rate can also be expressed as an infinitesimal change (or increase) in the concentration of the product with the infinitesimal change in time (dt).

Let dB be an infinitesimal change in the concentration of product B in time dt, then Rate \(=\frac{d[\mathrm{~B}]}{d t}=\frac{d x}{d t}\).

Hence,
Instantaneous rate \(=\frac{d x}{d t}\)

It is obtained from the slope of the curve obtained by plotting the concentration of the product against time.

The instantaneous rate is more useful in obtaining the rate law integrated equations.

Question ii.
Distinguish between order and molecularity of a reaction.
Answer:

Order	Molecularity
1. It is the sum of the exponents to which the concentration terms in rate law expression are raised.	1. ¡t is the number of molecules (or atoms or ions) of the reaCtants taking part in the elementary reaction.
2. It is experimentally determined and indicates the dependence of the reaction rate on the concentration of particular reactants.	2. It is the oretical property and indicátes the number of molecules of reactant in each step of the reaction.
3. It may have values that are integer, fractional, or zero.	3. It is always an integer.
4. Its value depends upon experimental conditions.	4. Its value does not depend upon experimental conditions.
5. It is the property of elementary and complex reactions.	5. It is the property of elementary reactions only.
6. Rate law expression describes the order of the reaction.	6. Rate law does not describe molecularity.

Question iii.
A reaction takes place in two steps,
1. NO(g) + Cl₂(g) NOCl₂(g)
2. NOCl₂(g) + NO(g) → 2NOCl(g)
a. Write the overall reaction.
b. Identify reaction intermediate.
c. What is the molecularity of each step?
Solution :
Given :
(1) NO_(g) + Cl_2(g) → NOCl_2(g)(2) NOCl_2(g) + NO_(g) → 2NOCl_(g)

(a) Overall reaction is obtained by adding both the reactions
2NO_(g) + Cl_2(g) → 2NOCl_2(g)(b) The reaction intermediate is NOCl₂, since it is formed in first step and consumed in the second step.
(c) Since the first step is a slow and rate determining step, the molecularity is two.

Since the second step is a fast step its molecularity is not considered.

Question iv.
Obtain the relationship between the rate constant and half-life of a fist order reaction.
Answer:
Consider the following reaction,

If [A]₀ and [A]t are the concentrations of A at start and after time t, then [A]₀ = a and [A]_t = a – x.

The velocity constant or the specific rate constant k for the first order reaction can be represented as,

where, a is the initial concentration of the reactant A, x is the concentration of the product B after time t, so that (a – x) is the concentration of the reactant A after time t.

Half-life of a reaction : The time required to reduce the concentration of the reactant to half of its initial value is called the half-life period or the half-life of the reaction.

If t_1/2 is the half-life of a reaction, then at t = t_1/2, x = a/2, hence a – x = a – a/2 = a/2

Hence, for a first order reaction, the half-life of the reaction is independent of the initial concentration of the reactant.

Question v.
How will you represent zeroth-order reaction graphically?
Answer:
(1) A graph of concentration against time : In case of a zero-order reaction, the rate of reaction is independent of the concentration of the reactant. The concentration [A]_t of the reactant at a time t is given by
[A]_t = – kt + [A]₀ (y = – mx + c)
where [A]₀ is the initial concentration of the reactant and k is a rate constant.

Hence in case of zero order reaction, when the concentration of the reactant is plotted against time, a straight line with the slope equal to – k is obtained. The concentration of the reactants de-crease with time. The intercept on the concentration axis gives the initial concentration, [A]₀.

(2) A graph of rate of a reaction against the concen-tration of the reactant: Rate of a zero order reaction is independent of the concentration of the reactant.

Rate, R = k [A]⁰ = k

Hence even if the concentration of the reactant decreases, the rate of the reaction remains constant.

Therefore if the rate of a zero order reaction is plotted against concentration, then a straight line with zero slope is obtained indicating, no change in the rate of the reaction with a change in the concentration of the reactants.

(3) A graph of half-life period against concentration : The half-life period of a zero-order reaction is given by, \(t_{1 / 2}=\frac{[\mathrm{A}]_{0}}{2 k}\) where [A]₀ is initial con-centration of the reactant and k is the rate constant. Hence the half-life period is directly proportional to the concentration.

When a graph of t_1/2 is plotted against concentration, a straight line passing through origin is obtained, and the slope gives \(\frac{1}{2 k}\), where k is the rate constant.

Question vi.
What are pseudo-fist order reactions? Give one example and explain why it is pseudo-fist order.
Answer:
Pseudo-first-order reaction : A reaction which has higher-order true rate law but is experimentally found to behave as first order is called pseudo first order reaction.
Explanation : Consider an acid hydrolysis reaction of an ester like methyl acetate.
CH₃COOCH_3(aq) + H₂O₍₁₎ \(\stackrel{\mathrm{H}_{(\mathrm{aq})}^{+}}{\longrightarrow}\) CH₃COOH_(aq) + CH₃OH_(aq)
Since the reaction involves two substances, ester and water, it is a bimolecular reaction and the true rate law should be, Rate = k’ [CH₃COOCH₃] x [H₂O]

Hence the reaction is expected to follow second order kinetics. However experimentally it is found that the reaction follows first order kinetics.

This is because solvent water being in a large excess, its concentration remains constant. Hence, [H₂O] = constant = k”
Rate = k [CH₃COOCH₃] x [H₂O]
= k [CH₃COOCH₃] x k”
= k’ x k” x [CH₃COOCH₃]
If k’ x k” = k, then Rate = k [CH₃COOCH₃],

This indicates that second-order true rate law is forced into first order rate law. Therefore this bimolecular reaction which appears of second order is called pseudo first order reaction.

Question vii.
What are the requirements for the colliding reactant molecules to lead to products?
Answer:
Collisions of reactant molecules : The basic requirements of a reaction is that the reacting species (atoms, ions or molecules) must come together and collide for a reaction to occur. Therefore the rate of the reaction shall depend on the rate and frequency of collisions which increase with the amount of reacting species and temperature.

Energy requirement (Activation energy) : The colliding molecules must possess a certain minimum energy called activation energy required far breaking and making bonds resulting in the reaction. This implies that the colliding molecules must have energy equal to or greater than the activation energy. The colliding molecules with less energy do not react.

Orientation of reactant molecules : The concept of activation energy is satisfactory in case of simple molecules or ions but not in case of complex or higher polyatomic molecules. It is observed that the rates of reaction are less as compared to the rates of collisions between activated molecules with activation energy.

This suggests that in addition, the colliding molecules must have proper orientations relative to each other during collisions. For example, consider the reaction, A – B + C → A + B – C. For the reaction to occur, C must collide with B while collisions with A will not be fruitful. Since B has to bond with C.

Question viii.
How catalyst increases the rate of reaction? Explain with the help of a potential energy diagram for catalyzed and uncatalyzed reactions.
Answer:
(i) A catalyst is a substance, when added to the reactants, increases the rate of the reaction without being consumed. For example, the decomposition of KClO₃ in the presence of small amount of MnO₂ is very fast but very slow in the absence of MnO₂.

2KClO_3(s) \(\frac{\mathrm{MnO}_{2}}{\Delta}\) 2KCl_(s) + 3O_2(g)

(ii) The phenomenon of catalysed reaction is called catalysis and depends on nature of the catalyst. In heterogeneous catalysis, the reactant molecules are adsorbed on the solid catalyst surface while in case of homogeneous catalysis, the catalyst reacts with one of the reactants, forms intermediate and decomposes reforming original catalyst and the products.

(iii) The catalyst provides alternative and lower energy path or mechanism for the reaction.

(iv) In the presence of the catalyst, the activation energy of the reaction is lowered. The height of activation energy barrier is less than that in the uncatalysed reaction.

(v) Due to lowering of energy of activation, (E_a) the number of molecules possessing E_a increases, hence the rate of the reaction increases.

(vi) The rate constant = k = A x e^-E_a/RT where A is a frequency factor and hence the rates of the catalysed reaction are higher than those of un-catalysed reactions.

(vii) The catalyst does not change the extent of the reaction but hastens the reaction.

(viii) The catalyst enters the reaction but does not appear in the balanced equation since it is consumed in one step and regenerated in the another.

Question ix.
Explain with the help of the Arrhenius equation, how does the rate of reaction changes with (a) temperature and (b) activation energy.
Answer:
(a) By Arrhenius equation, k = Ax e^-E_a/RTwhere k is rate constant, A is a frequency factor and Ed is energy of activation at temperature T. As E_a increases, the rate constant and rate of the reaction decreases.

(b) As temperature increases E_a/RT decreases but due to negative sign, k and rate increase with the increase in temperature.

Question x.
Derive the integrated rate law for first order reaction.
Answer:
Consider following gas phase reaction,

Let initial pressure of A be P₀ at t = 0. If after time t the pressure of a A decreases by jc then the partial pressures of the substances will be, P_A = P_Q – x; P_B= x and P_c = x

Total pressure will be,

P_T + P₀ – x + x + x = Po + x
∴ x = P_T – P_n

The partial pressures at time t will be,

Question xi.
How will you represent first-order reactions graphically.
Answer:
(1) A graph of rate of a reaction and concentration : The differential rate law for first-order reaction, A → Products is represented as, Rate = [/latex]-\frac{d[\mathrm{~A}]}{d t}=k[\mathrm{~A}]\(

∴ Rate = k x [A]_t (y = mx). When the rate of a first order reaction is plotted against concentration, [A]_t, a straight line graph is obtained.

With the increase in the concentration [A]_t, rate R, increases. The slope of the line gives the value of rate constant k.

(2) A graph of concentration against time : When the concentration of the reactant is plotted against time t, a curve is obtained. The concentration [A], of the reactant decreases exponentially with time. The variation in the concentration can be represented as,

where [A]₀ and [A]_t are initial and final concentrations the reactant and k is the rate constant. The time required to complete the first order reaction is infinity.

(3) A graph of log₁₀ (a – x) against time t :

When log₁₀(a – x) is plotted against time t, a straight line with negative slope is obtained, from which the velocity constant k can be calculated.

(4) A graph of half-life period and concentration : The half-life period, t_1/2 of a first order reaction is given by, where k is the rate constant.

For the given reaction at a constant temperature, t_1/2 is constant and independent of the concentration of the reactant.

Hence when a graph of t_1/2 is plotted against concentration, a straight line parallel to the concentration axis (slope = zero) is obtained.

(5) A graph of log₁₀ [latex]\left(\frac{a}{a-x}\right)\) against time : The rate constant, for a first order reaction is represented as, where [A₀] and [A]_t are the respective initial and final concentrations of the reactant after time t.

When \(\log _{10}\left(\frac{a}{a-x}\right)\) is plotted against time t, a straight line graph passing through the origin is obtained and the slope gives the value of k/2.303. From this slope, the rate constant can be calculated.

Question xii.
Derive the integrated rate law for the first order reaction, A(g) → B(g) + C(g) in terms of pressure.
Answer:
Consider following gas phase reaction,

Let initial pressure of A be P₀ at t = 0. If after time t the pressure of a A decreases by jc then the partial pressures of the substances will be, P_A = P_Q – x; P_B= x and P_c = x

Total pressure will be,

P_T + P₀ – x + x + x = Po + x
∴ x = P_T – P_n

The partial pressures at time t will be,

Question xiii.
What is zeroth-order reaction? Derive its integrated rate law. What are the units of rate constant?
Answer:
Definition : Zero order reaction : A reaction in which the rate of the reaction does not depend on the concentration of any reactant taking part in the reaction is called zero order reaction.

Consider a zero order reaction, A → Products
The rate of the reaction is, Rate \(=\frac{-d[\mathrm{~A}]}{d t}\)

By rate law,
Rate = k x [A]⁰ = k
∴ – d[A] = k x dt

If [A]₀ is the initial concentration of the reactant A at t = 0 and [A]_t is the concentration of A present after time t, then by integrating above equation,

This is the integrated rate law expression for rate constant for zero order reaction.
∴ k x t = [A]₀ – [A]_t
∴ [A]_t = – kt + A₀

For a zero order reaction :
The rate of reaction is R = k [A]⁰ = k
Hence, the velocity constant k has the unit of the rate of the reaction, i.e., mol dm^-3 s^-1.

Question xiv.
How will you determine activation energy: (a) graphically using Arrhenius equation (b) from rate constants at two different temperatures?
Answer:
(a) By Arrhenius equation,
Rate constant = = A x e^-E_a/RT where A is a fre-quency factor.

When log₁₀k is plotted against 1/T a straight line with negative slope is obtained. From the slope of the graph, energy of activation E_a, is obtained as follows :
Slope = \(\frac{E_{\mathrm{a}}}{2.303 R}\)
∴ Ea = 2303R x sloPe

(b) For the given reaction, rate constants k₁ and k₂ are measured at two different temperatures T₁ and T₂ respectively. Then \(\log _{10} \frac{k_{2}}{k_{1}}=\frac{E_{\mathrm{a}}\left(T_{2}-T_{1}\right)}{2.303 R \times T_{1} \times T_{2}}\) where E_a is the energy of activation.

Hence by substituting appropriate values, energy of activation E_a for the reaction is determined.

Question xv.
Explain graphically the effect of temperature on the rate of reaction.
Answer:
(i) It has been observed that the rates of chemical reactions increase with the increase in temperature.
(ii) The kinetic energy of the molecules increases with the increase in temperature. The fraction of molecules possessing minimum energy barrier,
i. e. activation energy E_a increases with increase in temperature.
(iii) Hence the fraction of colliding molecules that possess kinetic energy (E_a) also increases, hence the rate of the reaction increases with increase in temperature.

(iv) The above figure shows that the area that represents the fraction of molecules with kinetic energy exceeding E_a is greater at higher temperature T₂ than at lower temperature T₁. This explains that the rate of the reaction increases at higher temperature.
(v) The shaded area to the right of activation energy E_a represents fraction of collisions of activated molecules having energy E_a or greater.

Question xvi.
Explain graphically the effect of catalyst on the rate of reaction.
Answer:
(i) The phenomenon of catalysed reaction is called catalysis and depends on nature of the catalyst. In heterogeneous catalysis, the reactant molecules are adsorbed on the solid catalyst surface while in case of homogeneous catalysis, the catalyst reacts with one of the reactants, forms intermediate and decomposes reforming original catalyst and the products.
(ii) The catalyst provides alternative and lower energy path or mechanism for the reaction.
(iii) In the presence of the catalyst, the activation energy of the reaction is lowered. The height of activation energy barrier is less than that in the uncatalysed reaction.

Question xvii.
For the reaction 2A + B → products, find the rate law from the following data.

[A]/M	[A]/M	rate/M s^-1
0.3	0.05	0.15
0.6	0.05	0.30
0.6	0.2	1.20

Solution :
Given : 2A + B → Products
Rates : R₁ = 0.15 Ms^-1 R₂ = 0.3 Ms^-1[A]₁ = 0.3 M [A]₂ = 0.6 M
[B]₁ = 0.05 M [B]₂ = 0.05 M
(i) If order of the reaction in A is x and in B is y then, by rate law,

∴ y = 1. Hence the reaction has order one in B.
The order of overall reaction = n = n_A + n_B = 1 + 1 = 2

Answer:
(i) Rate law : Rate = fc [A] x [B]
Rate constant = k = 10M^-1s^-1Order of the reaction = 2

4. Solve

Question i.
In a first order reaction, the concentration of reactant decreases from 20 mmol dm^-3 to 8 mmol dm^-3 in 38 minutes. What is the half life of reaction? (28.7 min)
Solution :
Given: [A]₀ =20 mmol dm^-3;
[A]_t=8 mmol dm^-3; t=38 mm;

Answer:
Half life period = 28.74 min

Question ii.
The half life of a first order reaction is 1.7 hours. How long will it take for 20% of the reactant to react? (32.9 min)
Solution :
Given : t_1/2 = 1.7 hr; [A]₀ = 100;
[A]_t = 100 – 20 = 80; t =?
\(t_{1 / 2}=\frac{0.693}{k}\)

Answer:
Time required = t = 32.86 min

Question iii.
The energy of activation for a first order reaction is 104 kJ/mol. The rate constant at 25 0C is 3.7 × 10^-5 s^-1. What is the rate constant at 30⁰C? (R = 8.314 J/K mol) (7.4 × 10^-5)
Solution :

Answer:
k₂ = 7.382 x 10^-5 s^-1

Question iv.
What is the energy of activation of a reaction whose rate constant doubles when the temperature changes from 303 K to 313 K? (54.66 kJ/mol)
Solution :
Given : k₂ = 2k_t, T₁ = 303 K; T₂ = 313 K; E_a = ?

Answer:
Energy of activation = E_a = 54.66 kJ

Question v.
The rate constant of a reaction at 5000C is 1.6 × 10³ M^-1s^-1. What is the frequency factor of the reaction if its activation energy is 56 kJ/mol. (9.72 × 106 M^-1s^-1)
Solution :

Answer:
Frequency factor = A = 9.727 x 10⁶ M^-1s^-1

Question vi.
Show that time required for 99.9% completion of a first order reaction is three times the time required for 90% completion.
Solution :
Given : For 99.9 % completion, if [A]₀ = 100,

If t₁ and t₂ are the times required for 99.9 % and 90 % completion of reaction respectively, then

Answer:
Time required for 99.9 % completion of a first order reaction is three time the time required for 90 % completion of the reaction.

Question vii.
A first order reaction takes 40 minutes for 30% decomposition. Calculate its half life. (77.66 min)
Solution :

Answer:
Half life period = 77.70 min.

Question viii.
The rate constant for the first order reaction is given by log₁₀ k = 14.34 – 1.25 × 10⁴ T. Calculate activation energy of the reaction. (239.3 kJ/mol)
Solution :
Given : log₁₀ k = 14.34 – \(\frac{1.25 \times 10^{4}}{T}\) ……………………. (1)
From Arrhenius equation we can write,
\(\log _{10} k=\log _{10} A-\frac{E_{\mathrm{a}}}{2.303 R \times T}\) ……………………. (2)
By comparing equations (1) and (2),
\(\frac{E_{\mathrm{a}}}{2.303 \times R}\) = 1.25 x 10⁴
∴ Ea = 1.25 x 10⁴ x 2.303 x R
= 1.25 x 10⁴ x 2.303 x 8.314
= 23.93 x 10⁴ = 239.3 kJ mol^-1

[Note : Frequency factor A may also be calculated as follows : log₁₀ A = 14.34
∴ A = Antilog 14.34 = 2.188 x 10⁴
Answer:
Energy of activation = E_a = 239.3 kJ mol^-1.

Question ix.
What fraction of molecules in a gas at 300 K collide with an energy equal to activation energy of 50 kJ/mol? (2 × 10^-9)
Solution :
Given : T = 300 K; E_a = 50 kJ mol^-1
= 50 x 10³ mol^-1
The fraction of molecules undergoing fruitful collisions is

Answer:
Fraction of molecules undergoing collision = 2 x 10^-9

Activity :
1. If you wish to determine the reaction order and rate constant for the reaction, 2AB₂ → A₂ + 2B₂.
a) What data would you collect?
b) How would you use these data to determine whether the reaction is zeroth or first order?

2. The activation energy for two reactions are E_a and E’_a with E_a > E’_a. If the temperature of reacting system increases from T₁ to T₂, predict which of the following is correct?

k values are rate constants at lower temperatures and k values at higher temperatures.

12th Chemistry Digest Chapter 6 Chemical Kinetics Intext Questions and Answers

(Textbook Page No 121)

Question 1.
Write the expressions for rates of reaction for :
2N₂O_5(g) → 4NO_2(g) + O_2(g)?
Answer:
For the given reaction, Rate of reaction =
\(=R=-\frac{1}{2} \frac{d\left[\mathrm{~N}_{2} \mathrm{O}_{5}\right]}{d t}\)
\(\begin{aligned}
&=+\frac{1}{4} \frac{d\left[\mathrm{NO}_{2}\right]}{d t} \\
&=+\frac{d\left[\mathrm{O}_{2}\right]}{d t}
\end{aligned}\)

Problem 6.1: (Textbook Page No 121)

Question 1.
For the reaction,
\(\mathbf{3 I}_{(a q)}^{-}+\mathbf{S}_{2} \mathbf{O}_{8(a q)}^{2-} \longrightarrow \mathbf{I}_{3(\text { (aq) }}^{-}+2 \mathbf{S O}_{4(\mathrm{aq})}^{2-}\)
Calculate (a) the rate of formation of I₃^–,
(b) the rates of consumption of 1 and S₂O and (c) the overall rate of reaction if the rate of formation of \(\mathrm{SO}_{4}^{2-}\) is 0.O22 moles dm^-3 sec^-1.
Answer:

∴ (a) Rate of formation of \(\mathrm{I}_{3}^{-}\) = 0.011 mol dm^-3 s^-1
(b) Rate of consumption of I^– = 0.033 mol dm^-3 s^-1
(c) Rate of consumption of \(\mathrm{S}_{2} \mathrm{O}_{8}^{2-}\) = 0.011 mol dm^-3 s^-1
(d) Overall rate of reaction = Rate of consumption of reactant = Rate of formation of product

Try this….. (Textbook Page No 122)

Question 1.
For the reaction :
NO_2(g) + CO_(g) → NO_(g) + CO_2(g), the rate of reaction is experimentally found to be proportional to the square of the concentration of NO2 and independent that of CO. Write the rate law.
Answer:
Since the rate of the reaction is proportional to [NO₂]² and [CO]⁰, the rate law is R = k[NO₂]² x [CO]⁰
∴ R = k[NO₂]².

Try this….. (Textbook Page No 124)

Question 1.
The reaction,
CHCl_3(g) + Cl_2(g) → CCl_4(g) + HCl_(g) is first order in CHCl₃ and 1/2 order in Cl₂. Write the rate law and overall order of reaction.
Answer:
Since the reaction is first order in CHCl₃ and 1/2 order in Cl₂, the rate law for the reaction will be, Rate = k[CHCl₃] X [Cl₂]^1/2
The overall order (n) of the reaction will be, n = l + = \(\frac{1}{2}=\frac{3}{2}\)

Use your brain power! (Textbook Page No 124)

Question 1.
The rate of the reaction 2A + B → 2C + D is 6 x 10^-4 mol dm^-3 s^-1 when [A] =[B] = O.3 mol dm^-3 If the reaction is of first order in A and zeroth order in B, what is the rate constant?
Answer:
For the reaction,
2A + B → 2C + D,

(Problem 6.7) (Textbook Page No 126)

Question 1.
A reaction occurs in the following steps :
(i) NO_2(g) + F_2(g) → NO₂F_(g) + F_(g) (slow)
(ii) F_(g) + NO_2(g) → NO₂F_(g) (fast)
(a) Write the equation of overall reaction.
(b) Write down rate law.
(c) Identify the reaction intermediate.
Solution :
(a) The addition of two steps gives the overall reaction as
2NO_2(g) + F_2(g)→ 2NO₂F_(g)
(b) Step (i) is slow. The rate law of the reaction is predicted from its stoichiometry. Thus, rate = k [NO₂] [F₂]
(c) F is produced in step (i) and consumed in step (ii) hence F is the reaction intermediate.

Try this….. (Textbook Page No 126)

Question 1.
A complex reaction takes place in two steps :
(i) NO_(g) + O_3(g) → NO_3(g) + O_(g)
(ii) NO_3(g) + O_(g) → NO_2(g) + O_2(g)
The predicted rate law is rate = k [NO] [O₃]. Identify the rate-determining step. Write the overall reaction. Which is the reaction inter-mediate? Why?
Answer:
(i) NO_(g) + O_3(g) → NO_3(g) + O_(g)(ii) NO_3(g) + O_(g) →NO_2(g) + O_2(g)(a) The first step is slow and rate determining step since the rate depends on concentrations of NO_(g) and O_3(g). (Given : Rate = k [NO] x [O])
(b) The overall reaction is the combination of two steps.
NO_(g) ⁺ O_3(g)→ NO_2(g) + O_2(g)(c) NO_3(g) and O_(g) are reaction intermediates. They are formed in first step (i) and removed in the second step (ii).

Try this….. (Textbook Page No 129)

Question 1.
The half-life of a first-order reaction is 0.5 min. Calculate (a) time needed for the reactant to reduce to 20% and (b) the amount decomposed in 55 s.
Answer:

Try this….. (Textbook Page No 123)

Question 1.
For the reaction 2A + 2B → 2C + D, if concentration of A is doubled at constant [B] the rate increases by a factor of 4. If the concentration of B is doubled with [A] being constant the rate is doubled. Write the rate law of the reaction.
Answer:
Rate = R₁ = k[A]^x [B]^y
When concentration of A = [2A] and

Hence order with respect to A is 2 and with respect to B is 1. By rate law,
Rate = A: [A]² [B]

Question 2.
The rate law for the reaction A + B → C is found to be rate = k [A]² x [B]. The rate constant of the reaction at 25 °C is 6.25 M^-2 S^-1. What is the rate of reaction when [A] = 1.0 mol dm^-3 and [B] = 0.2 mol dm^-3?
Answer:
Rate = k x [A]² x [B]
= 6.25 x 1² x 0.2
Rate = 1.25 x 10² mol dm^-3 s^-1

12th Std Chemistry Questions And Answers:

12th Biology Chapter 2 Exercise Reproduction in Lower and Higher Animals Solutions Maharashtra Board

January 8, 2025January 7, 2025 by Prasanna

Balbharti Maharashtra State Board 12th Biology Textbook Solutions Chapter 2 Reproduction in Lower and Higher Animals Textbook Exercise Questions and Answers.

Reproduction in Lower and Higher Animals Class 12 Exercise Question Answers Solutions Maharashtra Board

Class 12 Biology Chapter 2 Exercise Solutions Maharashtra Board

Biology Class 12 Chapter 2 Exercise Solutions

1. Multiple choice questions

Question 1.
The number of nuclei present in a zygote is ……………….
(a) two
(b) one
(c) four
(d) eight
Answer:
(b) one

Question 2.
Which of these is the male reproductive organ in human?
(a) Sperm
(b) Seminal fluid
(c) Testes
(d) Ovary
Answer:
(c) Testes

Question 3.
Attachment of embryo to the wall of the uterus is known as ……………….
(a) fertilization
(b) gestation
(c) cleavage
(d) implantation
Answer:
(d) implantation

Question 4.
Rupturing of follicles and discharge of ova is known as ……………….
(a) capacitation
(b) gestation
(c) ovulation
(d) copulation
Answer:
(c) ovulation

Question 5.
In human females, the fertilized egg gets implanted in uterus ……………….
(a) after about 7 days of fertilization
(b) after about 30 days of fertilization
(c) after about two months of fertilization
(d) after about 3 weeks of fertilization
Answer:
(a) after about 7 days of fertilization

Question 6.
Test tube baby technique is called ……………….
(a) In vivo fertilization
(b) In situ fertilization
(c) In Vitro Fertilization
(d) Artificial Insemination
Answer:
(c) In Vitro Fertilization

Question 7.

The given figure shows a human sperm. Various parts of it are labelled as A, B, C, and D. Which labelled part represents acrosome?
(a) B.
(b) C
(c) D
(d) A
Answer:
(d) A

Question 8.
Presence of beard in boys is a ……………….
(a) primary sex organ
(b) secondary sexual character
(c) secondary sex organ
(d) primary sexual character
Answer:
(b) secondary sexual character

2. Very short answer questions

Question 1.
What is the difference between a foetus and an embryo?
Answer:
Embryo is a growing egg after fertilization until the main parts of the body and the internal organs have started to take shape while foetus is a stage which has the appearance of a fully developed offspring.

Question 2.
Outline the path of sperm up to the urethra.
Answer:
The path of sperm up to the urethra in male is as follows :
Seminiferous tubules → Rete testis → Vasa efferentia → Epididymis → Vas deferens → Ejaculatory ducts Urethra.

Question 3.
Which glands contribute fluids to the semen?
Answer:
The glands which contribute fluids to the semen are seminal vesicles, prostate gland.

Question 4.
Name the endocrine glands involved in maintaining the sexual characteristics of males.
Answer:
Interstitial cells of Leydig which lie in between the seminiferous tubules are involved in maintaining the sexual characteristics of male by secreting the male hormone androgen or testosterone. Adenohypophysis also regulates this secretion from the testis.

Question 5.
Where does fertilization and implantation occur?
Answer:
Fertilization of ovum takes place in the ampulla region of fallopian tube whereas implantation occur in the endometrium of uterus.

Question 6.
Enlist the external genital organs in female.
Answer:
The external genital organs in female include the following parts such as vestibule, labia minora, clitoris, labia majora and mons Veneris.

Question 8.
What is the difference between embryo and zygote?
Answer:
Zygote is the unicellular diploid structure formed as a result of fusion of sperm and ovum whereas embryo is a multicellular structure formed from zygote in the uterus 3 weeks after fertilization.

3. Fill in the blanks

Question 1.
The primary sex organ in human male is ……………….
Answer:
testis

Question 2.
The ……………… is also called the womb.
Answer:
uterus

Question 3.
Sperm fertilizes ovum in the ……………….. of fallopian tube.
Answer:
ampulla

Question 4.
The disc like structure which helps in the transfer of substances to and from the foetus’s body is called ………………..
Answer:
placenta

Question 5.
Gonorrhoea is caused by ……………….. bacteria.
Answer:
Neisseria gonorrhoeae

Question 6.
The hormone produced by the testis is ……………………
Answer:
testosterone / androgen.

4. Short Answer Questions

Question 1.
Budding in Hydra.
Answer:

Budding is a type of asexual reproduction method seen in Hydra.
Budding takes place during favourable period.
Towards the basal end of the body, small outgrowth is produced which is called a bud.
It grows and forms tentacles and gradually forms a new individual.
The young Hydra after complete development detaches from the parent and becomes an independent new organism.

Question 2.
Explain the different methods of reproduction occurring in sponges.
Answer:

Sponges reproduce both asexually and sexually and they also possess the power of regeneration. Their sexual reproduction is similar to higher animals even though their body organization is primitive type.
Asexual reproduction in sponges takes place by regeneration, budding and gemmule formation.
In sponges, during unfavourable period, gemmule is produced. It is an internal bud.
Archaeocytes which are dormant cells are seen in the aggregation in gemmule. These cells are capable of developing into a new organism.
Amoebocytes are other cells which secrete thick resistant layer of secretion which is coated around archaeocytes.
When favourable conditions of water and temperature return back, the gemmules can develop into new individuals by hatching, e.g. Spongilla.

Question 3.
IVF.
Answer:

In laboratory under sterile conditions, oocyte and sperms are placed in a test tube or glass plate to form a zygote. This process is called In Vitro Fertilization.
The zygote with 8 blastomeres is then transferred into the fallopian tube for further development.
IVF technique is used when childless couple wants to have a baby, but there are issues of sterility.
IVF is also called test tube baby technique.

Question 4.
Comment on any two mechanical contraceptive methods.
Answer:
Two mechanical contraceptive methods are as follows:
A. Condom or Nirodh:

It is a protective barrier in the form of thin rubber sheath which is used by male partner during the sexual coitus. It covers the penis and does not allow semen to flow during copulation.
Thus the entry of ejaculated semen into the female reproductive tract is obstructed. This can prevent conception. It is a simple and effective method and has no side effects.
“Nirodh” is a condom, most widely used in India as a contraceptive by males.
Condom also protects both the partners against sexually transmitted diseases such as AIDS and others.

B. Diaphragm, cervical caps and vaults:

Diaphragm and cervical caps are to be used by females as mechanical contraceptive measures.
They are made up of rubber. They are fitted on the cervix in vagina so that they prevent the entry of sperms into the uterus.
They are kept at least six hours after sexual intercourse in order to inhibit sperms from entering female genital tract.

Question 5.
Tubectomy.
Answer:

The permanent birth control method in women, is called tubectomy.
It is a surgical method, also called sterilization.
In tubectomy, a small part of the fallopian tube is tied and cut.
Tubectomy blocks transport of oocytes and also blocks sperms, thus preventing fertilization from reaching the oocyte.

Question 6.
Give the name of causal organism of Syphilis and write on its symptoms.
Answer:
1. Syphilis is a sexually transmitted veneral disease caused by a Spirochaete bacterium Treponema pallidum.

2. The site of infection is the mucous membrane in genital, rectal and oral region.

3. Symptoms of syphilis:

Primary lesion known as chancre at the site of infection.
They are seen on the external genitalia in males and inside the vagina in females.
Skin rashes accompanied by fever, inflammed joints and loss of hair.
Paralysis
Degenerative changes in the heart and brain.

Question 7.
What is colostrum?
Answer:

The fluid secreted by the mammary glands soon after childbirth is called colostrum.
Colostrum is the sticky and yellow fluid. It contains proteins, lactose and mother’s antibodies, e.g. IgA.
The fat content in colostrum is low.
The antibodies present in colostrum helps in developing resistance for the newborn baby at a time when its own immune response is not fully developed.

5. Answer the Following Questions

Question 1.
Describe the phases of menstrual cycle and their hormonal control.
Answer:
Menstrual cycle (Ovarian cycle):
i. Menstrual cycle involves a series of cyclic, changes in the ovary and uterus. The cyclic events are regulated by gonadotropins from pituitary and the hormones from ovary.
ii. The cyclic events in woman are repeated within approximately 28 days.
iii. Menstrual cycle is divided into following phases, viz.

Menstrual phase (Day 1-5)
Follicular phase in ovary that coincides with proliferative phase in uterus. Post menstrual phase (Day 5-14)
Ovulatory phase (Day 14-15)
Luteal phase in ovary which coincides with secretory phase in uterus (Day 16 to 28).

1. Menstrual Phase:

Menstrual phase occurs in the absence of fertilization.
During menstruation, uterine endometrium is sloughed off. Level of progesterone and estrogen decrease during this phase resulting into release of prostaglandins which cause this rupture.
Blood about 45-100 ml, tissue fluid, mucus, endometrial lining and unfertilized oocyte and other cellular debris is discharged through vagina as a menstrual flow. The endometrial lining becomes about 1 mm thin.
Fibrinolysin does not allow blood to clot during this period.
Pituitary starts secreting FSH, which further makes many primordial follicles to develop into primary and few of them into secondary follicles.

2. Proliferative phase/Follicular phase/Post menstrual phase:

During this phase in the ovary the follicles develop while in uterus the endometrium starts proliferating. 6 to 12 secondary follicles start developing but usually only one of them becomes Graafian follicle due to action of FSH.
Developing secondary follicles secrete the hormone estrogen.
Estrogen brings about regeneration of endometrium. Further proliferation of endometrium causes formation of endothelial cells, endometrial or uterine glands and network of blood vessels. Endometrium’s thickness becomes 3-5 mm.

(3) Ovulatory phase:

Ovulation occurs in this phase. Mature Graafian follicle ruptures and secondary oocyte is released into the pelvic region of abdomen.
Ovulation occurs due to surging quantity of LH from pituitary.

(4) Luteal phase/Secretary phase :
(i) Since the empty Graafian follicle converts itself into corpus luteum under the influence of LH, this phase is called luteal phase in ovary. At the same time, the uterine endometrium thickens and becomes more secretory and hence it is called secretory phase in uterus.

(ii) Corpus luteum secretes progesterone, some amount of estrogens and inhibin. These hormones stimulate the growth of endometrial glands which later start uterine secretions.

(iii) Endometrium becomes more vascularized becomes 8-10 mm. in thickness. These changes are the preparation for the implantation of the ovum if fertilization occurs.

(iv) In absence of fertilization, corpus luteum can survive for only two weeks and then degenerate into a non-secretory white scar called corpus albicans.

(v) If ovum is fertilized, woman becomes pregnant and hormone hCG (human Chorionic Gonadotropin) is secreted by chorionic membrane of embryo which keeps corpus luteum active till the formation of placenta.

Question 2.
Explain the steps of parturition.
Answer:
Parturition involves the following three steps:
1. Dilation stage:

Dilation stage means dilating the birth canal or passage though which baby is pushed out. In the beginning uterine contractions start from top and baby is moved to cervix. Due to compression of blood vessels and movements of flexible joints in pelvic girdle, mother experiences labour pains.
Oxytocin is secreted later in more amount causing severe uterine contractions. This pushes baby in a head down position and closer to cervix.
Cervix and vagina both are dilated.
This stage lasts for about 12 hours.
At the end, amniotic sac ruptures and amniotic fluid is passed out.

2. Expulsion stage:

During second stage of about 20 to 60 minutes, the uterine and abdominal contractions become stronger.
Foetus moves out with head down position through cervix and vagina.
The umbilical cord which connects the baby to placenta is tied and cut off close to the baby’s navel.

3. After birth or placental stage : In the last stage of 10 to 45 minutes, once the baby is out then the placenta is also separated from uterine wall and is expelled out as “after birth”. This is accompanied by severe contractions of the uterus.

Question 3.
Explain the histological structure of testis.
Answer:
Histological structure of testis:

The external covering of testis is a fibrous connective tissue called tunica albuginea.
Then there is an incomplete peritoneal covering called tunica vaginalis.
Interior to this there is a covering called tunica vascularis formed by capillaries.
The testis is composed of many seminiferous tubules that are lined by cuboidal germinal epithelial cells.
In the seminiferous tubules various stages of developing sperms are seen as spermatogenesis takes place here. These stages are spermatogonia, primary and secondary spermatocytes, spermatids and sperms.
Large, pyramidal sub tentacular cells, nurse cells or Sertoli cells are present between germinal epithelium. Sperm bundles remain attached to Sertoli cells with their heads.
Seminiferous tubules form sperms whereas Sertoli cells provide nourishment to the sperms till maturation.
In between the seminiferous tubules there are interstitial cells of Leydig which are endocrine in nature. They secrete testosterone.

Question 4.
Describe the structure of blastocyst or blastulation
Answer:

The outer layer of cells of the morula is called trophoblast or trophoectoderm. This layer absorbs the nutritive fluid secreted by uterine endometrial membrane.
As more and more fluid is absorbed by trophoblast cells, the cells become flat and a cavity called blastocyst cavity or blastocoel or segmentation cavity is formed.
This causes trophoblast cells to get separated from inner cell mass except at one side.
The trophoblast cells in contact with embryonal knob are known as cells of Rauber. As the quantity of fluid increases, the morula enlarges rapidly and assumes the shape of a cyst. This stage is called blastocyst.
The side of the blastocyst to which embryonal knob is attached is known as the embryonic or animal pole and the opposite side as abembryonic pole.
The trophoblast produces extra embryonic membranes and does not participate in the formation of embryo proper.
Zona pellucida disappears allowing the blastula to increase in size and volume. The blastocyst stage is reached in about five days after fertilization.
Blastocyst depends on mother for nutrition which it obtained through placenta.

Question 5.
Explain the histological structure of ovary in human.
Answer:
Histological structure of ovary:
(1) Each ovary is a compact structure differentiated into a central part called medulla and the outer part called cortex.

(2) The cortex is covered externally by a layer of germinal epithelium while the medulla contains the stroma or loose connective tissue with blood vessels, lymph vessels and nerve fibres.

(3) Different stages of developing ovarian follicles are seen in the cortex. Each primordial follicle has at its centre a large primary oocyte (2n) surrounded by a single layer of flat follicular cells, then gradually it matures.

(4) In the ovary during each menstrual cycle there is a maturation of primordial follicles into multilayered primary, secondary and Graafian follicles.

(5) Every Graafian follicle has three layers, viz. theca externa, theca interna and membrana granulosa which are from outer to inner side. A space called antrum filled with liquor folliculi is present inside the follicle. There is a small hillock of cells called cumulus oophours or discus proligerus over which the ovum is lodged. The ovum in turn is covered by vitelline membrane, zona pellucida and corona radiata from inner side to outer surface.

(6) Ovarian cortex also shows corpus luteum, or yellow body formed from empty Graafian follicle after ovulation. Corpus luteum is converted into corpus albicans or white body in case of absence of conception.

Question 6.
Describe the various methods of birth control to avoid pregnancy.
Answer:
Birth control/Contraceptive methods are of two main types, viz. temporary and permanent.
A. Temporary methods:
(1) Natural method/Safe period/Rhythm method : A week before and a week after menstrual bleeding is considered the safe period for sexual intercourse. It is based on the fact that ovulation occurs on the 14th day of menstrual cycle.

(2) Coitus Interruptus or withdrawal : In this method, the male partner withdraws his penis from the vagina before ejaculation, so as to avoid insemination. This method also has some drawbacks, as the pre-ejaculation fluid may contain sperms and this can cause fertilization.

(3) Lactational amenorrhoea (absence of menstruation) : This method is based on the fact that ovulation does not occur during the period of intense lactation following parturition so chances of conception are almost negligible. However, this method also has high chances of failure.

(4) Chemical means (spermicides) : In this method chemicals like foam, tablets, jellies and creams are introduced into the vagina before sexual intercourse, they adhere to the mucous membrane, immobilize and kill the sperms.

(5) Mechanical means/Barrier methods:
(i) Condom : It is a thin rubber sheath that is used to cover the penis of the male. Condom should be used before starting coital activity. It also prevents STDs and AIDS.

(ii) Diaphragm, cervical caps and vaults : These devices made of rubber are inserted into the female reproductive tract to cover the cervix diming copulation. They prevent conception by blocking the entry of sperms through the cervix.

(iii) Intra-uterine devices (IUDs) : These are plastic or metal objects placed in the uterus by a doctor. These include Lippes loop, copper releasing IUDs (Cu-T, Cu 7, multiload 375) and hormone releasing IUDs (LNG-20, progestasert). They prevent fertilization of the egg or implantation of the embryo.

(6) Physiological (Oral) Devices : Birth control pills (oral contraceptive pills) check ovulation as they inhibit the secretion of follicle stimulating hormone (FSH) and luteinizing hormone (LH) that are necessary for ovulation. The pill ‘Saheli’ is taken weekly.

(7) Other contraceptives : The birth control implant is similar to that of pills in their mode of action. It is implanted under the skin of the upper arm of the female.

B. Permanent methods surgical operations : In men surgical operation is called vasectomy and in women it is called tubectomy. This method blocks gamete transport and prevent pregnancy.

Question 7.
What are the goals of RCH programmes?
Answer:
Goals of RCH programmes are as follows:

Various aspects related to reproduction are made aware to general public.
Facilities are provided to people to understand and build up reproductive health.
Support is given for building up a reproductively healthy society.
Three critical health indicators, i.e. reducing total infertility rate, infant mortality rate and maternal mortality rate are well looked after.

Question 8.
What is parturition? Which hormones are involved in parturition?
Answer:

Parturition is the act of expelling out the mature foetus from the uterus of mother via the vagina.
When the foetus is fully mature, it starts secreting ACTH (Adreno Cortico Trophic Hormone) from its pituitary.
ACTH stimulates adrenal glands of foetus to produce corticosteroids.
These corticosteroids diffuse from foetal blood to mother’s blood across the placenta. Corticosteroids accumulate in mother’s blood that results in decreased amount of progesterone. Corticosteroids also increase secretion of prostaglandins.
Simultaneously estrogen levels rise bringing about initation of contractions of uterine muscular wall.
Reduced progesterone level and increased estrogen level cause secretion of oxytocin from mother’s pituitary. This causes greater stimulation of myometrium of uterus.
Prostaglandins cause increased forceful contraction of uterus which expels the foetus out of the uterus.
Hormone relaxin secreted by the placenta makes the pubic ligaments and sacroiliac joints of the mother loosen. This causes widening of birth canal which facilitates the normal birth of the baby.

Question 9.
What are the functions of male accessory glands?
OR
Write a brief account of accessory sex glands associated with human male reproductive system.
Answer:
Seminal Vesicles, prostate gland and Cowper’s glands are associated with human male reproductive system.
(i) Seminal Vesicles:

Seminal vesicles occur in pair present on the posterior side of urinary bladder. Its secretion consists about 60% of the total volume of the semen. The secretion is an alkaline seminal fluid containing fructose, fibrinogen and prostaglandins.
Fructose helps in the movement of sperms by providing energy to them.
Semen is coagulated in bolus by fibrinogen. This helps in faster movements of sperms in vagina after insemination.
Reverse peristalsis in vagina and uterus for faster movement of sperms towards the egg in the female body is elided by prostaglandins.

(ii) Prostate gland:

It is a single gland located under the urinary bladder. It has about 20 to 30 separate lobes which open separately into the urethra.
Prostatic fluid secreted by this gland is milky white and slightly acidic. It forms 30 % of the semen and is secreted in urethra.
Its contents are citric acid, acid phosphatase and various other enzymes.
The sperms are protected from the acidic environment of vagina by acid phosphatase.

(iii) Cowper’s glands (Bulbo-urethral glands):

Cowper’s glands occur in pair on either side of urethra. They are small and pea shaped.
Cowper’s glands secrete an alkaline, viscous, mucous-like fluid. It helps as lubricant during copulation.

Question 10.
What is capacitation? Give its importance.
Answer:

Capacitation is the process by which the sperms are made capable to swim up to the fallopian tubes. This process takes place in 5-6 hours.
50% of ejaculated sperms die due to unfavourable vaginal and uterine conditions.
The remaining sperms are capacitated with the help of prostaglandin and vestibular secretions of female tract. It involves the changes in the membrane covering the acrosome.
Due to capacitation, acrosome membrane becomes thin, Calcium ions enters the sperm and their tail begin to show rapid whiplash movements.
Sperms become extra active and then they ascend upwards to reach fallopian tubes.
After capacitation the sperms swim through the vagina and uterus and reach ampulla of fallopian tube within 5 minutes.

Long answer questions

Question 1.
Explain the following parts of male reproductive system along with labelled diagram showing these parts – Testis, vasa deferentia, epididymis, seminal vesicle, prostate gland and penis.
OR
With the help of a neat, labelled diagram, describe the human male reproductive system.
Answer:

(i) Testis, the male gonad, the accessory ducts and glands along with external genitalia form the male reproductive system.

(ii) Testes:

Testes are male gonads with dimensions of about 4.5. cm length, 2.5 cm width and 3 cm thickness.
There are about 200 to 300 lobules in each testis in which there are seminiferous tubules that form rete testis.
Testes produce sperms and secrete male sex hormone, androgen or testosterone.

(iii) Accessory ducts : Rete testis, vasa efferentia, epididymis, vas deferens, ejaculatory duct and urethra together form the accessory ducts of male reproductive system.
1. Vasa efferentia : Vasa efferentia are 12-20 fine tubules. They arise from rete testis and end into the epididymis. The sperms from the testis are carried by these ducts to the epididymis.

2. Epididymis : Epididymis are long and coiled tubes having three parts, viz. caput, corpus and cauda epididymis. They are located on the posterior border of each testis. The sperms undergo maturation in epididymis.

3. Vasa deferentia:

Vasa deferentia are a pair of 40 cm long tubular structures that arise from cauda epididymis.
Each vas deferens enters the abdominal cavity through the inguinal canal and then ascends in the form of spermatic cord.
Vas deferens of each side is joined by the duct from seminal vesicle to form ejaculatory duct.

4. Ejaculatory duct : About 2 cm long pair of ducts formed by joining of vas deferens and a duct of seminal vesicle are the ejaculatory ducts. Both ejaculatory ducts open into urethra near the prostate gland. Seminal fluid containing spermatozoa are carried by ejaculatory duct to the urethra.

5. Urethra : The male urethra provides a common passage for the urine and semen hence is also called urinogenital duct.

(iv) Accessory glands : Associated with male reproductive system are : (a) Seminal vesicles (b) Prostate gland and (c) Cowper’s or Bulbourethral glands. Every accessory gland has secretion which helps in functions of reproductive system.

(v) External genitalia : External genitalia consists of penis and scrotum.
1. Penis:

Penis is the copulatory organ used for insemination or deposition of sperms in female genital tract.
It is cylindrical, erectile and pendulous organ through which passes the urethra.
It contains three columns of erectile tissues which has abundant blood sinuses.
The tip is called glans penis while the retractible fold of skin on penis is called prepuce.

2. Scrotum : The scrotum is a pouch of pigmented skin arising from lower abdominal wall. It protects testes within it. Scrotum acts as thermoregulator. Testis are suspended in scrotum by spermatic cord.

Question 2.
Describe female reproductive system of human
Answer:

The female reproductive system consists of internal organs and external genitalia.

Internal organs are pair of ovaries and pair of fallopian ducts or oviducts, single median uterus and vagina. External genitalia is called vulva. There are a pair of vestibular glands in external genitalia. Mammary glands or breasts are also associated with reproductive system of female.

(1) Ovaries:

Ovaries are situated in the abdomen in upper lateral part of the pelvis near the kidneys. Their dimensions are about 3 cm in length, 1.5 cm in breadth and 1.0 cm thick. They are solid, oval or almond shaped organs.
Ovaries produce ova and they are also endocrine in nature as they produce estrogen, progesterone, relaxin, activin and inhibin.
Ovarian hormones bring about secondary sexual characters. They also control menstrual cycle, pregnancy and parturition.

(2) Fallopian tubes/oviducts:
(i) Fallopian tubes lie horizontally over peritoneal cavity. These are about 10 to 12 cm long, narrow, muscular structure lined by ciliated epithelium.
(ii) They transport the ovum after ovulation from the ovary to the uterus.
(iii) Fallopian tube can be subdivided into the following three parts:

The infundibulum which bears a number of finger-like processes called fimbriae at its free border.
Infundibulum is funnel-shaped having ostium which receives ova released from the ovary.
The second part is the ampulla where the fertilization takes place.
The last part is short cornua or isthmus which opens into the uterus.

(3) Uterus/Womb:
(i) Uterus is a pear-shaped, highly muscular, thick walled, hollow organ measuring about 8 cm in length, 5 cm in width and 2 cm in thickness.

(ii) Uterus has the following three parts : Fundus, Body or corpus and Cervix.

(iii) The cervix communicates above with the body of the uterus by an aperture, the internal os and with vagina below by an opening the external os.

(iv) Uterus has three-layered wall. These layers are:

Perimetrium : An outer serous layer.
Myometrium : The middle thick muscular layer of smooth muscles.
Endometrium : The inner highly vascular mucosa that has many uterine glands.

(v) Uterus receives the ovum from fallopian tube. It develops placenta during pregnancy for the nourishment of foetus. At the time of parturition, it expels the young one at birth.

(4) Vagina:

Vagina is a highly distensible fibro-muscular tube that lies between the cervix and the vestibule.
It is about 7 to 9 cm in length and is internally lined by stratified and non- keratinised epithelium. The vaginal wall has inner mucous lining.
Vagina acts as a birth canal as well as copulatory passage. It also allows passage of menstrual flow.
Vagina opens into vestibule by vaginal orifice which may be covered with hymen which is also a mucous membrane.

(5) External genitalia or vulva or pudendum : The external genitalia consists of five parts; viz. labia majora, labia minora, mons veneris, clitoris and vestibule.

(6) A pair of vestibular glands / Bartholin’s glands : These glands open into the vestibule and release a lubricating fluid.

(7) A pair of mammary glands/breasts : These are the accessory organs of female reproductive system for production and release of milk after parturition.

Question 3.
Describe the process of fertilization.
Answer:
(1) Fertilization is the process of fusion of the haploid male and female gametes which results in the formation of a diploid zygote (2n).

(2) In human beings fertilization is internal. Sperms deposited in vagina, swim across the uterus and fertilize the ovum in ampulla of the fallopian tube.

(3) Fertilization involves the following events:
(i) Insemination : Discharge of semen into the vagina at the time of copulation is called insemination.

(ii) Movement of sperm towards egg : Sperms reaching the vagina undergo capacitation process for 5-6 hours. During capacitation acrosomal membrane of sperm becomes thin and Ca⁺⁺ enters the sperm making it extra active. Sperms reach up to the ampulla by swimming aided with contraction of uterus and fallopian tubes. These contractions are stimulated by oxytocin of female. By capacitation sperm can reach ampulla within 5 minutes, they remain 5 viable for 24 to 48 hours, whereas ovum remains viable for 24 hours.

(iii) Entry of sperm into the egg : Though many sperms reach the ampulla, only a single sperm fertilizes the ovum. The acrosome of sperm after coming in contact with the ovum, releases lysins; hyaluronidase and corona penetrating enzymes. Due to these enzymes cells of corona radiata are separated and dissolved. The sperm head then passes through zona pellucida of egg. The zona pellucida has glycoprotein fertilizin receptor proteins. These bind to specific acid protein-antifertilizin of sperm. This makes sperm and ovum to come together. Fertilizin-Antifertilizin interaction is species- specific.

(iv) Acrosome reaction : When the sperm head comes in contact with the zona pellucida, its acrosome covering ruptures to release lytic enzymes, acrosin or zona lysin. These enzymes dissolve plasma membrane of egg so that the sperm nucleus and the centrioles enter the egg, while other parts remain outside. Now the vitelline membrane of egg changes into fertilization membrane which prevents any further entry of other sperms into the egg, thus polyspermy is prevented.

(v) Activation of ovum : After the entry of sperm head into ovum, it gets activated to resume and complete its meiosis-II. With this it gives out the second polar body. The germinal vesicle organises into female pronucleus. At this stage, it is true ovum.

(vi) Fusion of egg and sperm : The coverings of male and female pronuclei degenerate results in the formation of a synkaryon by a process called syngamy or karyogamy. The zygote is thus formed.

Question 4.
Explain the process by which zygote divides and redivides to form the morula.
Answer:
(1) Cleavage is a rapid mitotic division to form a blastula. These divisions takes place immediately after fertilization. The cells formed by cleavage are called blastomeres.

(2) The type of cleavage in human is holoblastic, i.e. the whole zygote gets divided, radial and indeterminate, i.e. fate of each blastomere is not predetermined.

(3) Cleavage show faster synthesis of DNA and high consumption of oxygen.

(4) Since there is no growth phase between the cleavages, the size of blastomeres will be reduced with every successive cleavage.

(5) The cleavages occur as follows:

(6) Successive divisions produce a solid ball of cells called morula of 16 cells. It consists of an outer layer of smaller clearer cells and an inner mass of larger cells.

(7) Morula reaches the uterus about 4-6 days after fertilization.

12th Std Biology Questions And Answers:

12th Biology Chapter 14 Exercise Ecosystems and Energy Flow Solutions Maharashtra Board

January 8, 2025January 7, 2025 by Prasanna

Balbharti Maharashtra State Board 12th Biology Textbook Solutions Chapter 14 Ecosystems and Energy Flow Textbook Exercise Questions and Answers.

Ecosystems and Energy Flow Class 12 Exercise Question Answers Solutions Maharashtra Board

Class 12 Biology Chapter 14 Exercise Solutions Maharashtra Board

Biology Class 12 Chapter 14 Exercise Solutions

1. Multiple choice questions

Question 1.
Which one of the following has the largest population in a food chain?
(a) Producers
(b) Primary consumers
(c) Secondary consumers
(d) Decomposers
Answer:
(a) Producers

Question 2.
The second trophic level in a lake is ……………………
(a) Phytoplankton
(b) Zooplankton
(c) Benthos
(d) Fishes
Answer:
(b) Zooplankton

Question 3.
Secondary consumers are …………………….
(a) Herbivores
(b) Producers
(c) Carnivores
(d) Autotrophs
Answer:
(c) Carnivores

Question 4.
What is the % of photosynthetically active radiation in the incident solar radiation?
(a) 100%
(b) 50%
(c) 1-5%
(d) 2-10%
Answer:
(b) 50%

Question 5.
Give the term used to express a community in its final stage of succession?
(a) End community
(b) Final community
(c) Climax community
(d) Dark community
Answer:
(c) Climax community

Question 6.
After landslide which of the following type of succession occurs?
(a) Primary
(b) Secondary
(c) Tertiary
(d) Climax
Answer:
(a) Primary

Question 7.
Which of the following is most often a limiting factor of the primary productivity in any ecosystem?
(a) Carbon
(b) Nitrogen
(c) Phosphorus
(d) Sulphur
Answer:
(c) Phosphorus

2. Very short answer question.

Question 1.
Give an example of ecosystem which shows inverted pyramid of numbers.
Answer:
Number of insects dependent on a single tree, is an example of ecosystem having inverted pyramid of numbers.

Question 2.
Give an example of ecosystem which shows inverted pyramid of biomass.
Answer:
Oceanic ecosystem has inverted pyramid of biomass.

Question 3.
Which mineral acts as limiting factor for productivity in an aquatic ecosystem?
Answer:
Phosphorus acts as limiting factor for productivity in an aquatic ecosystem.

Question 4.
Name the reservoir and sink of carbon in carbon cycle.
Answer:
Atmosphere is the reservoir of carbon cycle, while fossil fuels embedded in ocean and oceanic waters are the sink of carbon in carbon cycle.

3. Short answer questions.

Question 1.
Upright and inverted pyramid of biomass.
Answer:

Upright pyramid	Inverted pyramid
1. In upright pyramid, the number and biomass of the organisms which are at first trophic level of producers is high.	1. In inverted pyramid, the number and biomass of organisms at first trophic levels of producers is lowest.
2. The biomass goes on decreasing at each trophic level.	2. The biomass foes on increasing at each trophic level.
3. The base of the pyramid is always in large number of producers.	3. The base of pyramid is always in small numbers of producers.
4. Pyramid is always upright.	4. Pyramid is always inverted.

Question 2.
Food chain and Food web.
Answer:

Food chain	Food web
1. Food chain is the linear sequence of organisms for feeding purpose.	1. Food web is interconnections between many small food chains.
2. In food chain the flow of energy is through a single straight pathway from the lower trophic level to the higher trophic level.	2. In food web, the energy flow is interconnected through numerous food chains in the ecosystem.
3. In a food chain, members present at higher trophic level feeds on only single type of organisms.	3. In a food web, one organism can feed on multiple types of organisms.
4. Energy flow can be easily calculated in food chain.	4. Energy flow is difficult to calculate in a food web.
5. In food chain there is increased instability due to increasing number of separate and confined food chains.	5. In food web there is increased stability due to the presence of the complex food chains.
6. The whole food chain gets affected even if one group of an organism is disturbed.	6. The food web does not get disturbed by the removal of one group of organisms.
7. Member of higher trophic level depends or feed upon the single type of organisms of the lower trophic level.	7. The members of higher trophic level depend or feed upon many different types of the organism of the lower trophic level.
8. Food chain consists of only 4-6 trophic levels of different species.	8. Food web contains numerous trophic levels and also of different populations of species.
9. Competition is seen in members of same trophic level.	9. Competition is seen in members of same as well as different trophic levels.
10. Food chains are of two types: 1. Grazing food chain 2. Detritus food chain.	10. In food web there are no types.

4. Long answer questions

Question 1.
Define ecological pyramids and describe with examples, pyramids of number and biomass.
Answer:
1. Ecological Pyramids : Ecological Pyramids are the representation of relationships between different components of ecosystem at successive trophic levels.

2. Pyramid of numbers:

Pyramid of numbers is the diagrammatic representation which shows the relationship between producers, herbivores and carnivores at successive trophic levels in terms of their numbers.
As we go up the trophic levels, the interdependent organisms keep on reducing in their numbers.
For example, the number of grasses are more than the number of herbivores which eat them. The number of herbivores such as rabbits would be lesser than grass but greater than the carnivores that are dependent upon the population of rabbits.
Thus, the producers would be more than primary consumers and primary consumers would be more than secondary consumers. The top level consumers would be least in their numbers. This pyramid shows upright nature.

3. Pyramid of biomass:
(1) Pyramid of biomass are constructed by taking into consideration the different biomass in every successive trophic level.
(2) Pyramid of biomass in seas in inverted as the biomass of fishes is more than the biomass of phytoplankton.

Question 2.
What is primary productivity? Give brief description of factors that affect primary productivity.
Answer:
(1) Primary Productivity : The rate of generation of biomass in an ecosystem which is expressed in units of mass per unit surface (or volume) per unit time, for instance grams per square metre per day (g/m²/day) is called primary productivity.

(2) Primary productivity is described as gross primary productivity (GPP) and net primary productivity (NPP).

(3) The rate of production of organic matter during photosynthesis is called gross primary productivity of an ecosystem. Of this the amount of energy lost through respiration of plants is called respiratory losses.

(4) Gross primary productivity minus respiratory losses gives the net primary productivity (NPP).

(5) Net primary productivity is the available biomass for the consumption to heterotrophs (herbivores, carnivores and decomposers).

(6) Factors affecting primary productivity: Gross primary productivity (GPP) depends on the following factors:

Plant species inhabiting a particular area.
Variety of environmental factors such as temperature, sunlight, salinity, oxygen and carbon dioxide content, etc.
Availability of nutrients and
Photosynthetic capacity of plants.

Question 3.
Define decomposition and describe the processes and products of decomposition.
Answer:

Decomposition is the process carried out by the decomposer organisms.
Most of the bacteria, actinomycetes and fungi are decomposers. They convert the dead and decaying organic matter into simpler compounds. These simpler inorganic substances return back to the environment.
Decomposition takes place through detritus food chain. It starts from the dead organic matter. Detritus eating organisms called detritivores like earthworm, etc. breakdown the detritus into smaller fragments. Therefore, this first step of decomposition is called fragmentation.
Water soluble inorganic nutrients seep into the soil after fragmentation. These nutrients get precipitated as salts. Therefore, this second step of decomposition is called leaching.
The third step of decomposition is called catabolism. In this step, fungal and bacterial enzymes degrade the detritus into simple inorganic substances.
The partially decomposed organic matter is called humus which is formed by the process of humification. Humus is a dark coloured amorphous substance which is the reservoir of nutrients.
Humus too undergoes decomposition by bacterial action at a very slow rate and ultimately releases inorganic matter. This process is therefore called mineralization.
Decomposition requires oxygen in greater amount. The rate of decomposition is dependent upon the temperature and the humidity of the environment.

Question 4.
Write important features of a sedimentary cycle in an ecosystem.
Answer:

Reservoir of sedimentary cycles is earth’s crust.
The nutrients such as phosphorus which show sedimentary cycle, moves through hydrosphere, lithosphere and biosphere.
There is no respiratory release of nutrients into the atmosphere which show sedimentary cycle.
Natural reservoir of such nutrients are usually in the form of rocks. The rocks upon weathering release such nutrients into circulation.
Sedimentary cycles are very slow in their reactions.

Question 5.
Describe carbon cycle and add a note on the impact of human activities on carbon cycle.
Answer:
I. Carbon cycle:
(1) The entire carbon cycle has following basic processes viz. Photosynthesis, Respiration, Decomposition, Sedimentation and Combustion.

(2) Carbon is an important element as it forms 49% of the dry weight of all organisms. 71% of global carbon is present in the oceans. Therefore, ocean is the major reservoir of carbon. Carbon is also present in all fossil fuels. This is long term storage places or sinks for carbon which is in the form of coal, natural gas, etc.

(3) Respiration and photosynthesis are the two events that keep the carbon in cyclic circulation. During respiration, oxygen is used for combustion of carbohydrates as a result of which carbon dioxide and water are formed with the release of energy. The process of photosynthesis utilizes carbon dioxide and water vapour liberating oxygen and producing carbohydrates at the same time.

(4) Solar energy is stored in the carbon-carbon bonds of carbohydrates during photosynthesis whereas respiration releases the same stored energy.

(5) The main reservoirs for carbon dioxide are in the oceans and in rocks. Carbon dioxide is highly soluble in water and forms mild carbonic acid upon dissolving. This dissolved carbon dioxide precipitate as a solid rock or limestone which is calcium carbonate. This reaction in the seas is aided by corals and algae which in turn builds the coral reefs made up of limestone.

(6) Carbon moves through food chains. Autotrophic green plants on land and in water take up carbon dioxide and manufacture carbohydrates by the process of photosynthesis. The carbon stored in plants has three different fates, viz. liberation into atmosphere, consumption by animals upon feeding, storage in the plant till the plant dies.

(7) Animals get their carbon requirement through their food. When autotrophs are consumed, the heterotrophs obtain carbon. Carbon in animals also has three fates, viz. release back into the atmosphere in the process of respiration, release of stored carbon from the body by the action of decomposers or conversion into fossil fuels if buried intact.

(8) Fossil fuels such as coal, oil, natural gas, etc. can be mined and burned for energy purposes. This burning releases carbon dioxide back into the atmosphere.

(9) Carbon from limestone can also be released if pushed to the surfaces and slowly weathered away. Subducting and volcanic eruptions can also release the stored carbon from sediments.

II. Impact of human activities on carbon cycle:
(1) Excessive burning of fossils fuels for power plants, industrial processes and vehicular traffic, adds excessive carbon dioxide into atmosphere. When fossil fuels burn to run factories, power plants, motor vehicles, most of the carbon quickly enters the atmosphere as carbon dioxide gas.

(2) Each year, 5.5 billion tonnes of carbon is released through combustion of fossil fuels. Of this massive amount, 3.3 billion tonnes stays in the atmosphere.

(3) Rapid deforestation also increases carbon dioxide. Since plants absorb carbon dioxide for their photosynthesis, they always reduce the concentration of CO₂. But deforestation upsets this balance.

(4) Massive burning of fossil fuel for energy and transport, have significantly increased the rate of release of carbon dioxide into the atmosphere which is causing global warming and resultant climate change.

12th Std Biology Questions And Answers:

12th Chemistry Chapter 11 Exercise Alcohols, Phenols and Ethers Solutions Maharashtra Board

January 8, 2025January 7, 2025 by Bhagya

Balbharti Maharashtra State Board 12th Chemistry Textbook Solutions Chapter 11 Alcohols, Phenols and Ethers Textbook Exercise Questions and Answers.

Alcohols, Phenols and Ethers Class 12 Exercise Question Answers Solutions Maharashtra Board

Class 12 Chemistry Chapter 11 Exercise Solutions Maharashtra Board

Chemistry Class 12 Chapter 11 Exercise Solutions

1. Choose the correct option.

Question i.
Which of the following represents the increasing order of boiling points of (1), (2) and (3)?
(1) CH₃– CH₂– CH₂– CH₂– OH
(2) (CH₃)₂CH – O – CH₃
(3) (CH₃)₃COH
A. (1) < (2) < (3)
B. (2) < (1) < (3)
C. (3) < (2) < (1)
D. (2) < (3) < (1)
Answer:
(a) (1) < (2) < (3)

Question ii.
Which is the best reagent for carrying out following conversion ?

A. LiAlH₄
B. Conc. H₂SO₄, H₂O
C. H₂/Pd
D. B₂H₆, H₂O₂– NaOH
Answer:
B. Conc. H₂SO₄, H₂O

Question iii.
Which of the following reaction will give ionic organic product on reaction ?
A. CH₃– CH₂– OH + Na
B. CH₃– CH₂– OH + SOCl₂
C. CH₃– CH₂– OH + PCl₅
D. CH₃– CH₂– OH + H₂SO₄Answer:
C. CH₃– CH₂– OH + PCl₅

Question iv.
Which is the most resistant alcohol towards oxidation reaction among the follwoing ?

Answer:
(c)

Question v.
Resorcinol on distillation with zinc dust gives
A. Cyclohexane
B. Benzene
C. Toluene
D. Benzene-1, 3-diol
Answer:
(b) Benzene

Question vi.
Anisole on heating with concerntrated HI gives
A. Iodobenzene
B. Phenol + Methanol
C. Phenol + Iodomethane
D. Iodobenzene + methanol
Answer:
B. Phenol + Methanol

Question vii.
Which of the following is the least acidic compound ?

Answer:
(b)

Question viii.
The compound incapable of hydrogen bonding with water is ……

Answer:
(b)

Question ix.
Ethers are kept in air tight brown bottles because
A. Ethers absorb moisture
B. Ethers evaporate readily
C. Ethers oxidise to explosive peroxide
D. Ethers are inert
Answer:
C. Ethers oxidise to explosive peroxide

Question x.
Ethers reacts with cold and concentrated H₂SO₄ to form
A. oxonium salt
B. alkene
C. alkoxides
D. alcohols
Answer:
A. oxonium salt

2. Answer in one sentence/ word.

Question i.
Hydroboration-oxidation of propene gives…..
Answer:
n-propyl alcohol (CH₃ – CH₂ – CH₂ – OH)

Question ii.
Write the IUPAC name of alcohol having molecular formula C₄H₁₀O which is resistant towards oxidation.
Answer:

Question iii.
Write the structure of optically active alcohol having molecular formula C₄H₁₀O
Answer:

Question iv.
Write name of the electrophile used in Kolbe’s Reaction.
Answer:
Electrophile : Carbon dioxide (O = C = O)

3. Answer in brief.

Question i.
Why phenol is more acidic than ethyl alcohol ?
Answer:
(1) In ethyl alcohol, the -OH group is attached to sp³ – hybridised carbon while in phenols, it is attached to sp²– hybridised carbon.

(2) Due to higher electronegativity of sp²– hybridised carbon, electron density on oxygen decreases. This increases the polarity of O-H bond and results in more ionization of phenol than that of alcohols.

(3) Electron donating inductive effect (+1 effect) of the alkyl group destabilizes alkoxide ion. As a result alcohol does not ionize much in water, therefore alcohol is neutral compound in aqueous medium.

(4) In alkoxide ion, the negative charge is localized on oxygen, while in phenoxide ion the negative charge is delocalized. The delocalization of the negative charge (structure I to V) makes phenoxide ion more stable than that of phenol.

The delocalization of charge in phenol (structures VI to X), the resonating structures have charge separation (where oxygen atom of OH group to be positive and delocalization of negative charge over the ortho and para positions of aromatic ring) due to which phenol molecule is less stable than phenoxide ion. This favours ionization of phenol. Thus phenols are more acidic than ethyl alcohol.

Question ii.
Why p-nitrophenol is a stronger acid than phenol ?
Answer:
(1) In p-nitrophenol, nitro group (NO₂) is an electron withdrawing group present at para position which enhances the acidic strength (-1 effect). The O-H bond is under strain and release of proton (H⁺) becomes easy. Further p-nitrophenoxide ion is more stabilised due to resonance.

(2) Since the absence of electron withdrawing group (like – NO₂) in phenol at ortho and para position, the acidic strength of phenol is less than that of p-nitrophenol.

Question iii.
Write two points of difference between properties of phenol and ethyl alcohol.
Answer:

Question iv.
Give the reagents and conditions necessary to prepare phenol from
a. Chlorobenzene
b. Benzene sulfonic acid.
Answer:
(1) From chlorobenzene : Reagents required : NaOH and dil. HC1 Temperature : 623 K, Pressure : 150 atm
(2) From Benzene sulphonic acid : Reagents required : aq NaOH, caustic soda, dil. HC1 Temperature : 573 K

Question v.
Give the equations of the reactions for the preparation of phenol from isopropyl benzene.
Answer:
Preparation of phenol from cumene (isopropylbenzene) : This is the commercial method of preparation of phenol. When a stream of air is passed through cumene (isopropylbenzene) suspended in aqueous Na₂CO₃ solution in the presence of cobalt naphthenate catalyst, isopropyl benzene hydroperoxide or cumene hydroperoxide is formed. Isopropylbenzene hydroperoxide on warming with dil. H₂SO₄ gives phenol and acetone. Acetone is an important by-product of the reaction and is separated by distillation. The reaction is called auto oxidation.

Question vi.
Give a simple chemical test to distinguish between ethanol and ethyl bromide.
Answer:
When ethyl bromide is heated with aq NaOH; ethyl alcohol is formed whereas ethanol does not react with aq NaOH

4. An ether (A), C₅H₁₂O, when heated with excess of hot HI produce two alkyl halides which on hydrolysis form compound (B)and (C), oxidation of (B) gave and acid (D), whereas oxidation of (C) gave a ketone (E). Deduce the structural formula of (A), (B), (C), (D) and (E).
Answer:

5. Write structural formulae for

a. 3-Methoxyhexane
b. Methyl vinyl ether
c. 1-Ethylcyclohexanol
d. Pentane-1,4-diol
e. Cyclohex-2-en-1-ol
Answer:

6. Write IUPAC names of the following

Answer:

Activity :
• Collect information about production of ethanol as byproduct in sugar industry and its importance in fuel economy.
• Collect information about phenols used as antiseptics and polyphenols having antioxidant activity.

12th Chemistry Digest Chapter 11 Alcohols, Phenols and Ethers Intext Questions and Answers

Use your brain power! (Textbook Page No 235)

Question 1.
Classify the following alcohols as l0/2°/3° and allylic/benzylic

Answer:
(1) Ally lie alcohol (primary)
(2) Allylic alcohol (secondary)
(3) Allylic alcohol (tertiary)
(4) Benzylic alcohol (primary)
(5) Benzylic alcohol (secondary)

Use your brain power ….. (Textbook Page No 236)

Question 1.
Name t-butyl alcohol using carbinol system of nomenclature.
Answer:
Trimethyl carbinol.

Problem 11.1 (Textbook Page No 238)

Question 1.
Draw structures of following compounds:
(i) 2,5-DiethIphenoI
(ii) Prop-2-en-I-oI
(iii) 2-methoxypropane
(iv) Phenylmethanol
Solution :

Try this ….. (Textbook Page No 238)

Write IUPAC names ol (he following compounds.

Do you know (Textbook Page No 238)

Question 1.
The mechanism of hydration of ethylcnc to ethyl alcohol.
Answer:
The mechanism of hydration of ethylene involves three steps:

Step 1: Ethylene gets protonated to form carbocation by electrophilic attack of H₃O (Formation of carbocation intermediate).

Step 2 : Nucleophilic attack of water on carbocation

Step 3 : Deprotonation to form an alcohol

Problem 11.2 : (Textbook Page No 239)

Question 1.
Predict the products for the following reaction.

Solution:
The substrate (A) contains an isolated and an aldehyde group. H₂/Ni can reduce both these functional groups while LiAlH₄ can reduce only – CHO of the two, Hence

Try this ….. (Textbook page 240)

Question 1.
Arrange O – H, C – H and N – H bonds in increasing order of their bond polarity.
Answer:
Increasing order of polarity :C – H, N – H, O – H

Problem 11.3 : (Textbook Page No 241)

Question 1.
The boiling point of n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol and tert-butyl alcohol are 118 °C, 108 °C. 99 °C and 82 °C respectively. Explain.
Solution:
As branching increases, intermolecular van der Waal’s force become weaker and the boiling point decreases. Therefore, n-butyl alcohol has highest boiling point 118 °C and tert-butyl alcohol has lowest boiling point 83 °C. Isobutyl alcohol is a primary alcohol and hence its boiling point is higher than that of sec-butyl alcohol.

Problem 11.4 : (Textbook Page No 242)

The solubility of o-nitrophenol and p-nitrophenol is 0.2 g and 1.7 g/100 g of H₂O respectively. Explain the difference.
Solution :

p-Nitrophenol has strong intermolecular hydrogen bonding with solvent water. On the other hand, o-nitrophenol has strong intramolecular hydrogen bonding and therefore the intermolecular attraction towards solvent water is weak. The stronger the intermolecular attraction between solute and solvent higher is the solubility. Hence p-nitrophenol has higher solubility in water than that of o-nitrophenol.

Problem 11.5 : (Textbook Page No 243 & 244)

Question 1.
Arrange the following compounds in decreasing order of acid strength and justify.
(1) CH₃ – CH₂ – OH
(2) (CH₃)₃ C – OH
(3) C₆H₅ – OH
(4) p-NO₂ – C₆H₄ – OH
Solution :
Compounds (3) and (4) are phenols and therefore are more acidic than the alcohols (1) and (2). The acidic strengths of compounds depend upon stabilization of the corresponding conjugate bases. Hence let us compare electronic effects in the conjugate bases of these compounds :

The conjugate base of the alcohol (1) is destabilized by + 1 effect of one alkyl group, whereas conjugate base of the alcohol (2) is destabilized by +1 effect of three alkyl groups. Hence (2) is weaker acid than (1)

Phenols : The conjugate base of p-nitrophenol (4) is better resonance stabilized due to six resonance structures compared to the five resonance structure of conjugate base of phenol (3). The resonance structure VI has – ve charge on only electronegative oxygens. Hence the phenol (4) is stronger acid than (3). Thus the decreasing order of acid strength is (4), (3), (1), (2).

Use your brain power (Textbook Page No 244)

Question 1.
What are the electronic effects exerted by – OCH₃ and – Cl? Predict the acid strength of

Answer:
The electronic effects exerted by – Cl and – O CH₃ are as follows :
(1) Cl being more electronegative atom it pulls the bonding electrons towards itself. This is known as negative inductive effect (- I).

(2) – OCH₃ is less electronegative group which repels the bonding electrons away from it. This is known as positive inductive effect ( + I).

(3) The relative to parent phenol, is more acidic than .

Problem 11.6 : (Textbook Page No 245)

Question 1.
Mechanism of acid catalyzed dehydration of ethanol to give ethene.
Answer:
The mechanism of dehydration of ethanol involves the following order :
Step 1 : Formation of protonated alcohols : Initially ethyl alcohol gets protonated to form ethyl oxonium ion.

Step 2 : Formation of carbocation : It is the slowest step and hence, the rate determining step of the reaction.

Steps 3: Formation of ethene: Removal of a proton (H⁺) from carbocation.

The acidused in step I is released in step 3, the equilibrium is shifted to the right, ethene is removed as it is formed.

Problem 11.6 : (Textbook Page No 245)

Question 1.
Write the reaction showing major and minor products formed on heating butan-2-ol with concentrrated sulphuric acid.
Solution :
In the reaction described butan-2-ol undergoes dehydration to give but-2-ene (major) and but-l-ene (minor) in accordance with Saytzeff rule.

Problem 11.7 : (Textbook Page No 246)

Question 1.
Write and explain reactions to convert propan-l-ol into propan-2-ol.
Solution :
The dehydration of propane-l-ol to propene is the first step. Markownikoff hydration of propene is the second step to get the product propan-2-ol. This is brought about by reaction with concemtrated H₂SO₄ followed by hydrolysis.

Problem 11.8 : (Textbook Page No 246)

Question 1.
An organic compound gives hydrogen on reaction with sodium metal. It forms an aldehyde having molecular formula C₂H₄O on oxidation with pyridinium chlorochromate. Name the compounds and give equations of these reactions.
Solution :
The given molecular formula C₂H₄O of aldehyde is written as CH₃ – CHO. Hence the formula of alcohol from which this is obtained by oxidation must be CH₃ – CH₂ – OH. The two reactions can, therefore, be represented as follows :

(Do you know? Textbook Page No 248)

Question 90.
Write the mechanism of dehydration of alcohol to give ether.
Answer:
Dehydration of alcohols to form ether is SN₂ reaction. The mechanism of dehydration of ethanol involves the following steps.

Step 1 (Protonation) : Initially ethyl alcohol gets protonated in the presence of acid to form ethyl oxonium ion.

Step 2 (SN² mechanism) : Protonated alcohol species undergoes a backside attack by second molecule of alcohol is a slow step.

Step 3 (Deprotonation) : Formation of diethyl ether by elimination of proton

Problem 11.9 : (Textbook Page No 249)

Question 1.
Ethyl isopropyl ether does not form on reaction of sodium ethoxide and isopropyl chloride.

(i) What would be the main product of this reaction?
(ii) Write another reaction suitable for the preparation of ethyl isopropyl ether.
Solution :
(i) Isopropyl chloride is a secondary chloride. On treating with sodium ethoxide it gives elimination reaction to form propene as the main product.

(ii) Ethyl isopropyl ether can be prepared as follows using ethyl chloride (1⁰ chloride) as substrate.

Do you know? (Textbook Page No 250)

Question 1.
The mechanism of the reaction of HI with methoxy ethane.
Answer:
The reaction mechanism takes place as follows :
Step 1 : Protonation of ether Initially the ether molecule (methoxy ethane) protonated by cone. HI to form oxonium ion.

Step 2 : Iodide is a good nucleophile. It attacks the least substituted carbon of the oxonium ion formed in step 1 and displaces an alcohol molecule by SN² mechanism.

For example :
• Use of excess HI converts the alcohol into alkyl iodide.
• In case of ether having one tertiary alkyl group the reaction with hot HI follows SN1 mechanism, and tertiary iodide is formed rather than tertiary alcohol.

Step 1 :

Step 2 :

12th Std Chemistry Questions And Answers:

12th Biology Chapter 10 Exercise Human Health and Diseases Solutions Maharashtra Board

January 8, 2025January 7, 2025 by Prasanna

Balbharti Maharashtra State Board 12th Biology Textbook Solutions Chapter 10 Human Health and Diseases Textbook Exercise Questions and Answers.

Human Health and Diseases Class 12 Exercise Question Answers Solutions Maharashtra Board

Class 12 Biology Chapter 10 Exercise Solutions Maharashtra Board

Biology Class 12 Chapter 10 Exercise Solutions

1. Multiple Choice Questions

Question 1.
Which of the following is NOT caused by unsterilized needles?
(a) Elephantiasis
(b) AIDS
(e) Malaria
(d) Hepatitis
Answer:
(a) Elephantiasis

Question 2.
Opium derivative is …………………
(a) Codeine
(b) Caffeine
(c) Heroin
(d) Psilocybin
Answer:
(c) Heroin

Question 3.
The stimulant present in tea is …………………
(a) tannin
(b) cocaine
(C) caffeine
(d) crack
Answer:
(c) caffeine

Question 4.
WhIch of the following Is caused by smoking?
(a) Liver cirrhosis
(b) Pulmonary tuberculosis
(c) Emphysema
(d) Malaria
Answer:
(c) Emphysema

Question 5.
An antibody is …………………
(a) molecuic that binds specifically an antigen
(b) WBC which invades bacteria
(c) secretion of mammalian RBC
(d) cellular component of blood
Answer:
(a) molecule that binds specifically an antigen

Question 6.
The antiviral proteins released by a virus-infected cell are called …………………
(a) histamines
(b) interferons
(c) pyrogens
(d) allergens
Answer:
(b) interferons

Question 7.
Both B-cells and T-cells are derived from …………………
(a) lymph nodes
(b) thymus glands
(c) liver
(d) stem cells in bone marrow
Answer:
(b) thymus glands

Question 8.
Which of the following diseases can be contracted by droplet infection?
(a) Malaria
(b) Chicken pox
(c) Pneumonia
(d) Rabies
Answer:
(c) Pneumonia

Question 9.
Confirmatory test used for detecting HIV infection is …………………
(a) ELISA
(b) Western blot
(c) Widal test
(d) Eastern blot
Answer:
(b) Western blot

Question 10.
Elephantiasis is caused by …………………
(a) W. barterofti
(b) P. vivax
(c) Bedbug
(d) Elephant
Answer:
(a) W. bancrofti

Question 11.
Innate immunity is provided by …………………
(a) phagocytes
(b) antibody
(c) T-lymphocytes
(d) B-lymphocytes
Answer:
(c) T-lymphocytes

2. Short Answer Questions

Question 1.
What is the source of cocaine?
Answer:
Source of cocaine is coca plant – Erythroxylum coca.

Question 2.
Name one disease caused by smoking.
Answer:
Emphysema. (Damaged and enlarged lungs causing breathlessness)

Question 3.
Which cells stimulate B-cells to form antibodies ?
Answer:
Helper T-cells stimulate B-cells to form antibodies.

Question 4.
What does the abbreviation AIDS stand for?
Answer:
AIDS stands for Acquired Immuno Deficiency Syndrome.

Question 5.
Name the causative agent of typhoid fever.
Answer:
Salmonella typhi

Question 6.
What is Rh factor?
Answer:
Antigen ‘D’ present on the surface of RBCs is known as Rh factor.

Question 7
What is schizont?
Answer:
Schizont is a ring-like form produced from merozoites inside the erythrocytes of human beings, infected by Plasmodium, which again forms new merozoites.

Question 8.
Name the addicting component found in tobacco.
Answer:
Nicotine

Question 9.
Name the pathogen causing Malaria.
Answer:
Plasmodium vivax

Question 10.
Name the vector of Filariasis.
Answer:
Female Culex mosquito

Question 11.
Name of the causative agent of ringworm.
Answer:
Trichophyton

Question 12.
Health
Answer:
Health is defined as the state of complete physical, mental and social well¬being and not merely the absence of disease or infirmity.

3. Short Answer Questions

Question 1.
What are acquired diseases?
Answer:
Diseases which are developed after the birth of an individual are called acquired diseases. These are of two types, viz. (a) Communicable or infectious diseases and (b) Non- communicable or Non-infectious diseases. Communicable or infectious diseases are transmitted from infected person to another healthy person either directly or indirectly. They are caused due to pathogens like viruses, bacteria, fungi, helminth worms, etc. Non-communicable or Non-infectious diseases cannot be transmitted from infected person to another healthy one either directly or indirectly.

Question 2.
Antigen and antibody.
Answer:

Antigen	Antibody
1. Antigens are foreign proteins which are capable of producing infection.	1. Antibodies are immunoglobulins produced by the body to act against the antigens.
2. The structure of antigens is variable dependent upon the type of pathogen.	2. The structure of antibody is Y-shaped.
3. The antigen is the ‘non-self’ molecule.	3. The antibody is ‘self’ molecule.
4. The antigens have epitope sites which bind with the antibody molecule.	4. The antibodies have paratope sites which bind with the antigen molecule.

Question 3.
Name the infective stage of Plasmodium. Give Symptoms of malaria
Answer:
Sporozoite
I. Symptoms of malaria:

Fever accompanied by shivering.
Joint pain or arthralgia.
Vomiting.
Anaemia caused due to rupture of RBCs or haemolysis.
Haemoglobinuria.
Retinal damage.
Convulsions.
Cyclical occurrence of sudden coldness followed by rigor and then fever and sweating lasting for four to six hours. This is called a classic symptom of malaria.
Splenomegaly or enlarged spleen, severe headache, cerebral ischemia, hepatomegaly, i. e. enlarged liver, hypoglycaemia and haemoglobinuria with renal failure may occur in severe infections.

II. Spread / Transmission of malaria:

Malaria parasite is transmitted through the female Anopheles mosquito and hence it is known as mosquito-borne disease. Mosquito acts as a vector.
There are four species of Plasmodium, viz., P. vivax, P. falciparum, P. ovale and P. malariae which transmit malaria.

Question 4.
Explain the mode of infection and cause of elephantiasis.
Answer:
Mode of infection, i.e. transmission:

The parasite Wuchereria bancrofti is transmitted from a patient to other normal human being by female Culex mosquito.
The filarial larvae leave mosquito body and arrive on the human skin where they penetrate the skin and enter inside.
They undergo two moultings to become adults. Later they settle in the lymphatic system. They incubate for about 8-16 months.
When they settle in lymphatic system, this infection is called lymphatic filariasis.
The worms start infecting lymphatic circulation resulting into enlargement of lymph vessels and lymph nodes. The extremities like legs or limbs become swollen which resembles elephant legs. Therefore it is called elephantiasis.
This condition is lymphoedema, i.e. accumulation of lymph fluid in tissue causing swelling.

Question 5.
Why is smoking a bad habit?
Answer:

Smoking involves inhaling the cigarette smoke which contains nicotine and other toxic substances like N-nitrosodimethlene. There is some amount of carbon monoxide.
All these substances affect the normal respiratory health.
Smoking invites problems like asthma, hypertension, heart disease, stroke, lung damage.
The worst impact is that these substances are carcinogenic and hence can cause cancer of larynx, trachea, lung, etc.
Smoking not only affects the smokers but also has bad effect on others due to passive smokers.
In women, smoking is still hazardous as their ovaries can undergo mutations due to mutagenic chemicals found in smoke.
Therefore, smoking is a very bad habit.

Question 6.
What do the abbreviations AMIS and CMIS denote?
Answer:
AMIS is Antibody-mediated immune system or humoral immunity and CMIS is cell- mediated immune system.

Question 7.
What is a carcinogen? Name one chemical carcinogen with its target tissue.
Answer:

Carcinogen is the substance or agent that causes cancer.
Urinary bladder cancer caused by 2-naphthylamine and 4-aminobiphenyl.

Question 8.
Active immunity and passive immunity.
Answer:

Active immunity	Passive immunity
1. Active immunity is produced in response to entry of pathogens and their antigenic stimuli.	1. Passive immunity is produced due to antibodies that are transferred to the body.
2. Active immunity is the long lasting immunity.	2. Passive immunity is short-lived immunity.
3. In active immunity, the body produces its own antibodies.	3. In passive immunity, antibodies are given to the body from outside.
4. Natural acquired active immunity is obtained due to infections by pathogens.	4. Natural acquired passive immunity is obtained through antibodies of mother transmitted- to baby by placenta or colostrum.
5. Artificial acquired active immunity is obtained through vaccinations. These vaccines contain dead or live but attenuated pathogens.	5. Artificial acquired passive immunity is also obtained through vaccinations, but here the vaccines contain the readymade antibodies which are prepared with the help of other animals such as horses.

4. Short Answer Questions

Question 1.
B-cells and T-cells.
Answer:

B-cells	T-cells.
1. B-cells are type of lymphocyte whose origin is in bone marrow but maturation is in blood.	1. T-cells are type of lymphocytes which originate in bone marrow but maturation occurs in thymus.
2. B-cells Eire type of lymphocytes which are involved in humoral mediated immunity.	2. T-cells are type of lymphocytes which are involved in cell-mediated immunity.
3. 20% of lymphocytes present in the blood are B-cells.	3. 80% of lymphocytes present in the blood are T-cells.
4. Two types of B-cells are Memory cells and Plasma cells.	4. T-cells are of following subtypes : Cytotoxic T-cells, helper T-cells, suppressor T-cells.
5. They are involved in antibody mediated immunity. (AMI)	5. They are involved in cell-mediated immunity (CMI).
6. B-cells produced antibodies with which they fight against pathogens.	6. T-cells do not produce antibodies.
7. B-cells have membrane bound immunoglobulins located on the surface.	7. There is a presence of T cell receptors on the T-cell surface.

Question 2.
What are the symptoms of malaria? How does malaria spread?
Answer:
Symptoms of malaria:

Fever accompanied by shivering.
Joint pain or arthralgia.
Vomiting.
Anaemia caused due to rupture of RBCs or haemolysis.
Haemoglobinuria.

Question 3.
AIDS.
Answer:
(1) AIDS or the acquired immuno deficiency syndrome, is fatal viral disease caused by a retrovirus (ss RNA) known as the human immuno deficiency virus (HIV) which weakens the body’s immune system. It is called a modern pandemic.

(2) The HIV attacks the immune system which in turn causes many opportunistic infections, neurological disorders and unusual malignancies ultimately leading to death.

(3) AIDS was first noticed in USA in 1981 whereas in India, first confirmed case of AIDS was in April 1986 from Tamil Nadu.

(4) HIV is transmitted through body fluids such as saliva, tears, nervous system tissue, spinal fluid, blood, semen, vaginal fluid and breast milk. However, only blood, semen, vaginal secretions and breast milk generally transmit infection to others.

(5) The transmission of HIV occurs by sexual contact, through blood and blood products and by contaminated syringes, needles, etc. There is also transplacental transmission or through breast milk at the time of nursing.

(6) Accidental needle injury, artificial insemination with infected donated semen and transplantation with infected organs are some of the rare occasions of transmission of HIV.

(7) HIV infection is not spread by casual contact such as hugging, bite of mosquitoes or using other objects touched by a patient.

(8) Acute HIV infection progresses over time to asymptomatic HIV infection and then to early symptomatic HIV infection. Later, it progresses to full blown AIDS when patient shows advanced HIV infection with CD4 T-cell count below 200 cells/mm.

Question 4.
Give the symptoms of cancer.
Answer:
Symptoms of cancer:

Presence of lump or tumour.
White patches in the mouth.
Change in a wart or mole on the skin.
Swollen or enlarged lymph nodes.
Vertigo, headaches or seizures if cancer affect the brain.
Coughing and shortness of breath if lungs are affected due to cancer.

Question 5.
Antigens on blood cells.
Answer:

There are about 30 known antigens on the surface of human red blood cells. They decide the type of blood group such as ABO, Rh, Duffy, Kidd, Lewis, P MNS, Bombay.
The different blood groups are determined genetically due to presence of a particular antigen.
Landsteiner found two antigens or agglutinogens on the surface of human red blood cells which are named as antigen A and antigen B.
There is another antigen called Antigen D which decides the Rh status of the blood. If Antigen D is present, the person is said to be RH positive and when it is lacking, the person is Rh negative.
These antigens are responsible for types of blood group and the specific transfusions.
Antigens present on the RBCs and antibodies present in the serum can cause agglutination reactions if they are non-compatible. Therefore, at the time of transfusion blood groups are checked properly.

Question 6.
Antigen-antibody complex:
Img 1
Answer:

Between antigen and antibody there is specificity.
Each antibody is specific for a particular antigen.
On the antigens there are combining sites which are called antigenic determinants or epitopes.
Epitopes react with the corresponding antigen binding sites of antibodies which are called paratopes.
The antigen binding sites are located on the variable regions of the antibody. Variable regions have small variations which make each antibody highly specific for a particular antigen.
Owing to variable region the antibody can recognize the specific antigen.
Antibody thus binds to specific antigen in a lock and key manner, forming an antigen- antibody complex.

Question 7.
What are the various public health measures, which you would suggest as safeguard against infectious diseases?
Answer:
Infectious diseases spread through pathogens, therefore, it is an important duty of each person to decrease the risk of infecting our own self or others. This can be achieved by

Washing hands often, especially whenever, we are in contact with food and water. Before and after preparing food, before eating and after using the toilet, hand wash is a must.
Vaccinations : Immunization helps us to protect against contracting many diseases. Therefore, timely vaccination should be taken. Especially at the time of epidemic, one must keep distance from infected area or get vaccinated.
One must be at home if there are signs and symptoms of an infection. By going out, we may infect other healthy persons.
Proper diet and exercise should be followed to improve one’s own immunity.
Hygiene should be utmost in the kitchen and dining area. One must take care while eating uncovered and leftover food.
Bathroom and toilet should be cleaned daily as there can be a high concentration of bacteria or other infectious agents in these areas.
One should have responsible sexual behaviour to avoid sexually transmitted diseases.
Personal items such as toothbrush, comb, towel, undergarments or razor blade should never be shared.
Travelling should be avoided because we may infect other passengers during travel. Moreover, our illness can be aggravated. Some special immunizations are needed during certain travels, such as anti-cholera vaccine while going to Pandharpur during Ashadhi.

Question 8.
How does the transmission of each of the following diseases take place?
(a) Amoebiasis:
Answer:
Amoebiasis is usually transmitted by the following ways:

The faecal-oral route.
Through contact with dirty hands or objects.
By anal-oral contact.
Through contaminated food and water.

(b) Malaria:
Answer:
Symptoms of malaria:

Fever accompanied by shivering.
Joint pain or arthralgia.
Vomiting.
Anaemia caused due to rupture of RBCs or haemolysis.
Haemoglobinuria.

Unsafe and unhygienic food and drinks contaminated with the eggs of Ascaris are the main mode of transmission.
Eggs hatch inside the intestine of the new host.
The larvae pass through various organs and settle as adults in the digestive system.

(d) Pneumonia:
Answer:

Pneumonia usually spreads by direct person to person contact.
It is also spread via droplet infection, i.e. droplets released by infected person.
Using clothes and utensils of the patient.

Question 9.
What measures would you take to prevent water-borne diseases?
Answer:

To prevent water-borne diseases, use of safe, clean and potable water is a must. Water should be filtered, then boiled and stored in covered container. If possible water purifier systems should be installed at home.
One should preferably use bottled water or carry our own water container while travelling.
Cleaning of water containers and maintaining personal hygiene near water storage is a must.
Megacities offer chlorinated and purified water for citizens. But villages and smaller rural set ups use river water which may be highly contaminated with pathogens. Such water should be purified before consumption to prevent water-borne diseases.

Question 10.
Typhoid.
Answer:
Typhoid is an infective disease caused by Gram-ve bacterium, Salmonella typhi.
(1) It is food and water-borne infection. In the intestinal lumen of infected person this bacteria is found.

(2) The bacterium has “O” – antigen, which is a lipopolysaccharide (LPS), present on surface coat and its flagella has “H” – antigen. Thus it becomes pathogenic.

(3) Signs and Symptoms of typhoid are as follows:
Prolonged and high fever with nausea, fatigue, headache.
Abdominal pain, constipation or diarrhoea. In severe cases rose-coloured rash is seen on skin. Tongue shows white coating and there is cough. Anorexia or loss of appetite is seen. In chronic cases there is breathlessness, irregular heartbeats and haemorrhage.

(4) Poor hygiene habits and poor sanitation and insects like houseflies and cockroaches spread typhoid.

(5) Typhoid is diagnosed by Widal test.

(6) Antibiotics like Chloromycetin can cure typhoid. Preventive vaccines such as oral Ty21a vaccine and injectable typhim vi and typherix against typhoid are also available. Chronic cases need surgical removal of gall bladder.

5. Match the following.

Column I	Column II
(a) AIDS	(i) Antibody production
(b) Lysozyme	(ii) Activation of B-cells
(c) B-cells	(iii) Immunoglobulin
(d) T-helper cells	(iv) Tears
(e) Antibody	(v) Immuno deficiency

Answer:

Column I	Column II
(a) AIDS	(v) Immuno deficiency
(b) Lysozyme	(iv) Tears
(c) B-cells	(i) Antibody production
(d) T-helper cells	(ii) Activation of B-cells
(e) Antibody	(iii) Immunoglobulin

6. Long Answer Questions

Question 1.
Describe the structure of antibody.
Answer:
Img 2

Antibodies are highly specific to specific antigens. They are glycoprotein called immunoglobulins (Igs.).
They are produced by plasma cells. Plasma cells are in turn formed by B-lymphocytes.
About 2000 molecules of antibodies are formed per second by the plasma cells.
Antibody is a ‘Y’-shaped molecule. It has four polypeptide chains, two heavy or H-chains and two light or L-chains.
Disulfide bonds (-s-s-) hold the polypeptide chains together to form a ‘Y’-shaped structure.
The region holding arms and stem of antibody is termed as hinge. Each chain of the antibody has two distinct regions, the variable region and the constant region.
Variable regions have a paratope which is an antigen-binding site. This part of antibody recognizes and binds to the specific antigen forming an antigen-antibody complex.
Antibodies are called bivalent as they carry two antigen binding sites.

Question 2.
Vaccination.
Answer:

Vaccines are prepared from inactivated pathogen, in the form of protein or sugar from pathogen or dead form of pathogen or toxoid from pathogens or attenuated pathogen.
These when they are administered to a person to protect against a particular pathogen, it is called vaccination.
Vaccination ’teaches’ the immune system to recognize and eliminate pathogenic organism. Because, already in the body the vaccine is injected and body has made antibodies in response to it. Thus, body is prepared before the attack, if at all it is exposed to pathogen.
Thus, it is an important form of primary prevention, which reduces the chances of illness by protecting people. It works by exposing the pathogen in a safe form.
Vaccinations control spread of diseases like measles, polio, tetanus and whooping cough that once threatened many lives.
Vaccination controls the epidemic outbreak of diseases, if all the people Eire pre-vaccinated.
Some hazardous diseases like small, pox and polio have been completely eradicated by the vaccination.

Question 3.
What is cancer? Differentiate between benign tumour and malignant tumour. The main five types of cancer
Answer:
I. Cancer : Cancer is a disease caused by uncontrolled cell division due to disturbed cell cycle.

II. Difference between benign tumour and malignant tumour:

Benign tumour	malignant tumour
1. Benign tumour is localized and it does not spread to neighbouring areas.	1. Malignant tumour starts as local but spreads rapidly to neighbouring areas.
2. Benign tumour is enclosed in connective tissue sheath.	2. Malignant tumour is not enclosed in connective tissue sheath.
3. Benign tumour compresses the surrounding normal tissue.	3. Malignant tumour invades and destroys the surrounding tissue.
4. Benign tumours can be removed surgically.	4. Malignant tumours need further treatment after removal.
5. Except for brain tumour, benign tumours are usually not fatal.	5. Malignant tumours are fatal.
6. Benign tumours do not show metastasis.	6. Malignant tumours show metastasis.
7. Benign tumours are well differentiated.	7. Malignant tumours are poorly differentiated.
8. Benign tumours show slow and progressive growth.	8. Malignant tumours show rapid and erratic growth.

III. The main five types of cancer:

Types of Cancer : According to the tissue affected, the cancers are classified into five main types. These are as follows:

Carcinoma : Cancer of epithelial tissue covering or lining the body organs is known as carcinoma. E.g. breast cancer, lung cancer, cancer of stomach, skin cancer, etc.
Sarcoma : Cancer of connective tissue is called sarcoma. Following are the types of sarcoma osteosarcoma (bone cancer), myosarcoma (muscle cancer),
chondrosarcoma (cancer of cartilage) and liposarcoma (cancer of adipose tissue).
Lymphoma : Cancer of lymphatic tissue is called lymphoma. Lymphatic nodes, spleen and tissues of immune system are affected due to lymphoma.
Leukaemia : Leukaemia is blood cancer. In this condition, excessive formation of leucocytes take place in the bone marrow. There are millions of abnormal immature leucocytes which cannot fight infections. Monocytic leukaemia, lymphoblastic leukaemia, etc. are the types of leukaemia.
Adenocarcinoma : Cancer of glandular tissues such as thyroid, pituitary, adrenal, etc. is called adenocarcinoma.

Question 4.
Describe the different type of immunity.
Answer: There are two basic types of immunity, viz. innate immunity and acquired immunity.
(A) Innate immunity:

Innate immunity is natural, inborn immunity, which helps the body to fight against the invasion of microorganisms.
Innate immunity is non-specific because it does not depend on previous exposure to foreign substances.
Innate immunity mechanisms consist of various types of barriers such as anatomical barriers, physiological barriers, phagocytic barriers and inflammatory barriers. They prevent entry of foreign agents into the body.

(B) Acquired immunity:

The immunity that an individual acquires during his life is called acquired immunity or adaptive immunity or specific immunity. It helps the body to adapt by fighting against specific antigens hence it is called adaptive immunity. Since it is produced specifically against an antigen, it is called specific immunity.
Acquired immunity takes long time for its activation.
This type of immunity is seen only in vertebrates.
Due to acquired immunity, the body is able to defend against any invading foreign agent.

Question 5.
Describe the ill-effects of alcoholism on health.
Answer:

Alcohol in any form is toxic for the body. Hence as soon as alcohol is consumed, the liver tries to detoxify it.
In low doses it acts as a stimulant but in high dose, it acts on central nervous system, especially the cerebrum and cerebellum. Still higher dose can induce a comatose condition.
Alcohol affect the gastrointestinal tract by causing inflammation and damage to gastric 4 mucosa. Ulceration and painful condition arises in alcoholics.
Excessive doses of alcohol induce vomiting.
The worst effect of alcohol is on liver causing diseases like cirrhosis.
Alcohol induces hypertension and cardiac problems.
Apart from physical effect, it causes deterioration of mental health and emotional well-being.
Alcoholic person cannot think due to numbness in his/her cerebrum.
The social health is greatly affected as the alcoholic can cause problems to his family, friends and society in general.

Question 6.
In your view, what motivates the youngsters to take to alcohol or drugs and how can this be avoided?
Answer:
I. Taking drugs or alcohol:

Youngsters are at the vulnerable age, where they lack the planning about their future.
If they fall into bad company or are facing parental neglect, they get hooked on to alcohol or drugs.
Some common causes for addiction among youngsters are insufficient parental supervision and monitoring or excessive pressure and expectations from them. Lack of communication between an adolescent and parents.
Poorly defined rules for the family. Continuous family conflicts.
Favourable parental attitudes towards alcohol and drug uses. Many a times, at home children are exposed to such habits.
Inability to cope up with present and hence switching to the addictions. Risk taking behaviour which is common among youngsters.

II. Methods/measures to avoid drug abuse:

There should be complete acceptance for the child, because the adolescent phase is the most crucial phase when the children should be treated with love, care and respect.
Many physical, hormonal and psychological transformations are taking place in this phase. Therefore child suffers from stressful situation.
Wrong company and bad influence of peer group can trap the child in bad addictive habits. Thus, family should be supportive and communicative to help such children.
The sexual thoughts should be sublimed by channelizing energy into healthy pursuits like sports, reading, music, yoga and other extracurricular activities.
Ill-effects of drugs or alcohol should be told to youngsters.
Education and counselling can control the children from getting hooked on to the addictions.

Question 7.
Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?
Answer:
Friends can influence one to take alcohol and drugs, if a boy or girl is timid and non-communicative with his or her parents and teachers. It also depends on the personality of the indtvidual. In the adolescent age, many fall in trap due to such peer pressure. The confusion in the mind and role of hormones playing on the psyche and thought process makes one unable to understand the hazards of such habits. Also there is curiosity to do these experimentations due to bad influence of media.

If there is complete trust and friendship with sensible parents, then such influence does not work. One should protect himself or herself by a strong denial. Communicating such incidents to an elder in whom a boy or girl can confide, is very important. One should tell his or her friends about the ill-effects of alcohol and drugs. He should be made aware of these aspects that he or she has learnt in this lesson.

12th Std Biology Questions And Answers: