Download CLS Aipmt 17 18 XII Zoo Study Package 4 SET 1 Chapter 4 PDF

TitleCLS Aipmt 17 18 XII Zoo Study Package 4 SET 1 Chapter 4
Tags Homo Natural Selection Paleontology Fossil
File Size796.2 KB
Total Pages12
Document Text Contents
Page 1

Aakash Educational Services Pvt. Ltd. Regd. Office : Aakash Tower, 8, Pusa Road, New Delhi-110005 Ph.011-47623456

Solutions

SECTION - A

School/Board Exam. Type Questions

Very Short Answer Type Questions :

1. Which theory of origin of life says that the life on earth came from outerspace?

Sol. Theory of Panspermia/Cosmic/Cosmozoan theory.

2. Name the sail ship in which Darwin travelled.

Sol. H.M.S. Beagle.

3. Give one example of analogy in plants.

Sol. Sweet potato and potato.

4. Do placental mammals in Australia also show adaptive radiation like marsupials? Give the answer in yes or

no.

Sol. Yes.

5. What is the essence of Darwinian theory about evolution?

Sol. Natural selection.

6. Name one biologist famous for his work on populations.

Sol. Thomas Malthus.

7. How do mutations arise in a population?

Sol. Mutations arise suddenly in a population.

8. If q is the frequency of occurrence of an allele A, then what is the probability of individuals with genotype AA?

Sol. q2.

9. Progymnosperms originated in which period?

Sol. Turtles, Tortoises and Crocodiles. Devonian.

10. The fossils discovered in Java belonged to which ancestor of man?

Sol. Homo erectus.

Chapter 4

Evolution

Page 2

40 Evolution Solution of Assignment (Set-1)

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Short Answer Type Questions :

11. Name the gases used by Miller in his experiment and which theory was more or less accepted by his experiment.

Sol. Miller used CH
4
, H

2
, NH

3
and water vapour at 800°C in a closed flask in his experiment. The theory of chemical

evolution of life; as proposed by Oparin and Haldane, was more or less accepted by his experiment.

12. Explain why do we say that when we see stars we apparently are peeping into the past?

Sol. This is because we can only see an object when the light emitted by it reaches our eyes. Now stars are

trillions of kilometres away from us and hence, the light emitted by them would have started its journey millions

of years back. That is why it is said that when we see stars we apparently are peeping into the past.

13. How the concept of ‘common ancestor’ was explained/concluded by Darwin?

Sol. While on his sea voyage, Darwin observed that various living forms share similarities in their structure and

behaviour among themselves and also with the life forms that have extinct from earth millions of years ago.

Darwin concluded that similarities among unrelated organisms can only arise when they are descended from

common ancestors. Hence, like this the concept of ‘common ancestor’ came into his mind.

14. Which characteristics are selected by the nature?

Sol. Those characteristics which enable some organisms to survive better than others in various natural conditions

including food scarcity, harsh climatic conditions etc; are selected by the nature.

15. What do you mean by the term palaeontology?

Sol. Paleontology studies the history of past life on earth through fossils. Fossils are the paleontological evidences

of evolution. Fossils are the pressured remains of those life-forms that have become extinct millions of years

ago from earth.

16. How can you say that homology indicates common ancestry?

Sol. As we know the homologous organs are anatomically similar but due to adaptations to different habitats, they

developed different functions according to the need. Hence, the similar structures having common origin,

diverged to adapt different habitats. Hence, it shows that homology indicates common ancestry.

17. Why did predators spot the white-winged moths more than dark-winged moths after industrialisation set in?

Sol. It easy for a predator bird to spot a moth against a contrasting background. The smoke and soots deposited

on the tree trunks caused the darkening of latter. Hence, it was easy for the predators to spot white-winged

moths against the dark background of trunks of trees after industrialisation set in.

18. How Darwin came to the conclusion of adaptive radiation in Galapagos Islands?

Sol. In Galapagos Islands, Darwin observed an amazing diversity of creatures and his special attention went to some

small black birds. He realised that these birds were of many varieties with different beaks and feeding habits

but still they shared similarities. Hence, he concluded that these all birds arose from a common ancestor which

was seed-eater and various varieties arose from a common ancestor through adaptive radiation.

19. When ‘more than one’ adaptive radiation occurs in an isolated geographical area, how can it be called

convergent evolution? Exemplify.

Page 6

44 Evolution Solution of Assignment (Set-1)

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37. (i) What do you mean by the ‘biochemical similarities’?

(ii) What do you infer by the presence of biochemical similarities?

Sol. (i) Biochemical similarities refer to the similarities in the proteins and genes. The proteins and genes are

present at the subcellular level, i.e., they are the components of cells. Even different looking organisms

can have similarities in their genes (the segments of chromosomes) and proteins present in their cells.

(ii) These similarities point towards the ‘common ancestry’. It is because if the proteins and genes performing

a given function are found to be similar in two organisms, it shows that these two organisms share

common ancestor in their history. If the similarities are more, they are more related and if less, then they

are less related but related.

38. Anthropogenic actions can lead to speciation. Explain this with suitable examples.

Sol. Hint : Antibiotic resistance in bacteria and herbicides, pesticides resistant varieties.

39. Study the figure given below and answer the following questions.

(i) Which animals are depicted in the given figure?

(ii) What phenomenon they are representing?

(iii) How can you say that these are the result of that phenomenon?

Sol. (i) Given figure depicts the Australian marsupials all of which evolved on the Australian island continent.

(ii) They are representing the phenomenon of adaptive radiation.

(iii) These all marsupials are different from each other in their habitats and modes of living. All are the different

species. But they all evolved from the single ancestral stock representing that they have radiated in an

isolated geographical area from the single species. Hence, it is said that they are the result of adaptive

radiation.

Page 7

45Solution of Assignment (Set-1) Evolution

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40. Study the picture given below and answer.

(i) Which animals are depicted on the left and right side of the picture respectively?

(ii) How are they related to one another?

(iii) Their relation points towards which phenomenon?

Sol. (i) On the left side of the picture, placental mammals are shown and on the right side, marsupials are shown.

(Both present on the Australian island).

(ii) Mammals on the left side are placental, i.e., they show true placenta formation during pregnancy unlike

the marsupials on the right side. The placental mammals appear similar to the marsupials depicted

adjacent to them. These two types of mammals not only ‘appear’ similar but also they have similar modes

of living. For example, flying squirrel is a placental mammal which appears similar to flying phalanger which

is a marsupial.

(iii) Their similarities in appearances and modes of living show that they are the result of convergent evolution.

Because due to living in the same habitat, they developed similarities in their structures and modes of living.

Page 11

49Solution of Assignment (Set-1) Evolution

Aakash Educational Services Pvt. Ltd. Regd. Office : Aakash Tower, 8, Pusa Road, New Delhi-110005 Ph.011-47623456

21. Discuss in brief the evolution of reptiles on earth.

Sol. The reptiles evolved from the amphibians. Early reptiles have become extinct from earth but their modern day

descendents like turtles, tortoises, crocodiles, etc. are existing on the earth. For nearly 200 million years after

they evolved, the reptiles dominated on earth. About 200 mya, some of these reptiles went back to the water

to evolve into fish-like reptiles. The land reptiles were dinosaurs, largest of which was Tyrannosaurus rex. The

dinosaurs got extinct suddenly about 65 mya.

Long Answer Type Questions :

22. Study the figure given below and answer the questions following it.

1 2 3 4

(i) Write down your observations on the varieties seen in the Darwin’s finches shown above.

(ii) How did Darwin explain the existence of different varieties of finches on Galapagos Islands?

Or

(a)



(b)

(i) Write your observations on the figure depicted above.

(ii) What was the explanation put forth for this observation?

Sol. Hints : (i) Different shapes of beaks and their feeding habits.

(ii) Adaptive radiation of finches.

Or

Hints : (i) Effect of industrialisation on the number of moths.

(ii) Explanation, the predators will spot the moth against a contrasting background.

23. (i) What do you understand by genetic equilibrium?

(ii) How gene migration affects the Hardy-Weinberg equilibrium?

Or

(i) Discuss in brief about Dryopithecus, Ramapithecus and Australopithecines.

(ii) How Neanderthal man is related to modern Homo sapiens? Give the time of existence on earth and cranial

capacity of the Neanderthal man.

Sol. (i) Genetic equilibrium means that gene pool of a population remains constant and the frequencies of

occurrence of its various alleles are stable. This equilibrium points towards the stability of allelic frequencies

in a population until and unless this equilibrium is not disturbed by any kind of evolutionary force. For

example, in a diploid organism, if p is the frequency of allele A, then the probability of appearance of A

on both the chromosomes is p
2
. It is expected value. But when frequency of this allele A measured is

found to be different from p
2
, it indicates disturbance in the genetic equilibrium which points towards the

evolution.

Page 12

50 Evolution Solution of Assignment (Set-1)

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(ii) Gene migration is one of the ‘evolutionary force’ that tends to affect the Hardy-Weinberg equilibrium (or

genetic equilibrium). When a segment of population migrates from one population to another, it results in

the ‘transfer’ of genes from old to new one, resulting in addition of new alleles/genes in the new population

and vice versa, therefore, disturbing the genetic equilibrium.

Or

(i) Dryopithecus : Ancestor of modern day apes as it was more ape-like. It existed 15 mya on earth. It had

semierect posture. It used to eat soft fruits and leaves. It used to live mainly on trees. They were more

ape like.

Ramapithecus : It was more man-like and lived on the tree tops but also walked on the grounds. Its jaws

and teeth were like that of humans. They used to eat hard nuts and seeds. They were more man like.

Dryopithecus and Ramapithecus : were hairy and walked like gorillas and chimpanzees.

Australopithecus : It had erect posture and had human as well as ape characters.

(ii) The Neanderthal man is the ancestor of modern Homo sapiens. It lived in near east and central Asia

between 1,00,000–40,000 years back and had a brain size of 1400cc.

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