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Chapter: 12th Zoology : Chapter 6 : Evolution

Evolution: Questions and Answers (Evaluation)

Zoology : Evolution : Book Back Questions Answers: Choose the Correct Answers, Short Answers, brief Answers, Important Questions and Answers



1) The first life on earth originated

a) in air

b) on land

c) in water

d) on mountain

Answer: c) in water


2) Who published the book “Origin of species by Natural Selection” in 1859?

a) Charles Darwin

b) Lamarck

c) Weismann

d) Hugo de Vries

Answer: a) Charles Darwin


3) Which of the following was the contribution of Hugo de Vries?

a) Theory of mutation

b) Theory of natural Selection

c) Theory of inheritance of acquired characters

d) Germplasm theory

Answer: a) Theory of mutation


4) The wings of birds and butterflies is an example of

a) Adaptive radiation

b) convergent evolution

c) divergent evolution

d) variation

Answer: b) convergent evolution


5) The phenomenon of “ Industrial Melanism” demonstrates

a) Natural selection

b) induced mutation

c) reproductive isolation

d) geographical isolation

Answer: a) Natural selection


6) Darwin’s finches are an excellent example of

a) connecting links

b) seasonal migration

c) adaptive radiation

d) parasitism

Answer: c) adaptive radiation


7) Who proposed the Germplasm theory?

a) Darwin

b) August Weismann

c) Lamarck

d) Alfred Wallace

Answer: b) August Weismann


8) The age of fossils can be determined by

a) electron microscope

b) weighing the fossils

c) carbon dating

d) analysis of bones

Answer: c) carbon dating


9) Fossils are generally found in

a) igneous rocks

b) metamorphic rocks

c) volcanic rocks

d) sedimentary rocks

Answer: d) sedimentary rocks


10) Evolutionary history of an organism is called

a) ancestry

b) ontogeny

c) phylogeny

d) paleontology

Answer: c) phylogeny


11) The golden age of reptiles was

a) Mesozoic era

b) Cenozoic era

c) Paleozoic era

d) Proterozoic era

Answer: a) Mesozoic era


12) Which period was called “Age of fishes”?

a) Permian

b) Triassic

c) Devonian

d) Ordovician

Answer: c) Devonian


13) Modern man belongs to which period?

a) Quaternary

b) Cretaceous

c) Silurian

d) Cambrian

Answer: a) Quaternary


14) The Neanderthal man had the brain capacity of

a) 650 – 800cc

b) 1200cc

c) 900cc

d) 1400cc

Answer: d) 1400cc


15) List out the major gases seems to be found in the primitive earth.

The primitive earth had no proper atmosphere

It consisted of ammonia, methane, hydrogen and water vapour.

Uv rays split water molecules into hydrogen and oxygen.

Ammonia and methane combined with oxygen to form carbondioxide and other gases.


16) Explain the three major categories in which fossilization occur?

1) Actual Remains.

Original hard parts like bone, teeth and shells are preserved.

Hard parts of marine animals like bones, shells are sedimented.

They are protected from deterioration.

Salinity of ocean prevents decay.

Woolly mammoths (22000 yrs ago) preserved in the frozen Siberian coast.

Human beings and animals of ancient city of Pompeii preserved in volcanic ash from Mount Vesuvius.

2) Petrifaction

Original body portions of dead animals were replaced molecule for molecule by minerals.

Original substance got disintegrated.

Principal minerals involved are iron pyrites, silica, calcium carbonate and bicarbonates of calcium, magnesium.

Natural moulds and casts :


Impressions of animals on soft mud harden into stones. These are moulds.


The cavities of moulds are filled up with hard minerals. They get fossilized. They are called casts.


Faecal matter were hardened into tiny pellets called coprolites. From this we understand the nature of diet of prehistoric animals.


17) Differentiate between divergent evolution and convergent evolution with one example for each.

Divergent Evolution

Homologous structures bring about divergent evolution.

Homologous structures are similar in origin. They perform different functions.

Examples in animals

Vertebrate to forelimbs have anatomical similarity (similar bones like humerus, radius, ulna, carpals, metacarpals, phalanges.)

Example in plants

Thorn of Bougainvillea and tendrils of cucurbita, Pisum sativum.

Thorn - defence

Tendril - climbing.

Convergent Evolution

Analogous structures bring about convergent evolution.

Analogous structures have different structural patterns but similar function.

Example in animals

Eyes of octopus, mammals

Flipper of penguin, dolphin

Example in plants

Root modification in sweet potatoes

Stem modification in potato

Both are having common function - storage of food.


18) How does Hardy-Weinberg’s expression (p2+2pq+q2=1) explain that genetic equilibrium is maintained in a population? List any four factors that can disturb the genetic equilibrium.

In a population of beetles there are 2 colours

Dark Grey colour is determined by the (Black) genes 'AA' and 'Aa'.

Light grey colour is due to the genes 'aa'.

The frequency of AA is = p2

The frequency of Aa is = 2pq

The frequency of aa is = q2

Genotype frequency can be estimated by Hardy- weinberg equation.

(p+q)2 = P2 + 2pq + q2

p = 0.3, q= 0.7

p2= (0.3)2 = 0.09 = 9% AA

2pq = 2(0.3) (0.7) = 0.42 = 42% Aa

q2 = (0.7)2 0.49 =4 9% aa

So, the beetle population is in Hardy-weinberg equilibrium

Four factors disturbing genetic equilibrium

Gene flow


Genetic drift


Natural selection.


19) Explain how mutations, natural selection and genetic drift affect Hardy Weinberg equilibrium.

Hardy Weinberg stated that the allele frequencies in a population are stable.

They are constant from generation to generation in the absence of gene flow, genetic drift, mutation, recombination and natural selection.

For example in a wolf population, there may be a shift in the frequency of a gene variant for black fur than grey fur. This type of change is due to natural selection or migration etc.


20) How did Darwin explain fitness of organisms?

According to Darwin the fitness is the useful variation of organism.

It helps the organism to overcome the struggle.

Such variations are passed on to the next generation.

He proved that fittest organisms can survive and leave more progenies than the unfit ones through natural selection.

Struggle for existence resulted in the survival of the fittest. Such organisms become better adapted to the changed environment.


21) Mention the main objections to Darwinism.

Failed to explain the mechanism of variation.

Explains the survival of the fittest not the arrival of the fittest.

Darwin focused on small fluctuating non-heritable variations.

Did not distinguish somatic and germinal variation.

He could not explain the vestigeal organs, over specialisation.

Ex) Large tusk in extinct mammoth (over specialization) oversized antler in Irish deer.


22) Taking the example of Peppered moth, explain the action of natural selection. What do you call the above phenomenon?

Industrial Melanism.

Example : Natural selection exhibited by the peppered moth (Biston betularia)

In England before industrialization, the peppered moth were in 2 colours, white and black.

Pre-industrialization witnessed white coloured background in the building walls.

So, the white coloured moths escaped from predators in white background.

During post-industrialization, the tree trunks became dark by smoke, soot.

Black moths camouflaged in dark background.

White moths were easily identified by the predators.

Dark coloured moth population was selected. Their number increased.

Nature offered positive selection pressure to the black moths.

Adaptable organisms increase in population through natural selection.


23) Darwin's finches and Australian marsupials are suitable examples of adaptive radiation – Justify the statement.

Adaptive Radiation

It is an evolutionary process.

A new species diverge from a single ancestral form. It becomes adapted to newly invaded habitat.

Darwin's finches

2 million years ago, their common ancestor arrived on the Galapagos islands.

Darwins finches evolved into 14 recognized species.

They differ in body size, beak shape and feeding behaviour.

Change in size and form of beak helped to use different food like insects, seeds, nectar fro cactus flowers and blood of iguanas.

Marsupials in Australia

100 millon years ago, they came from the common ancestor and evolved independently.

Marsupials have undergone adaptive radiation. They occupy diverse habitat in Australia.


24) Who disproved Lamarck’s Theory of acquired characters? How?

Lamarck's Theory of Acquired characters, was disproved by August Weismann.

He conducted experiments on mice. He cut their tails for 20 generations and breeding them.

All mice were bom with tails.

Change in somatoplasm will not be transferred to the next generation.

Changes in the germplasm will be inherited.


25) How does Mutation theory of De Vries differ from Lamarck and Darwin’s view in the origin of new species.

Mutations theory of Devries

Mutations are sudden random change that occur in an organism. It is not inheritable. Example: He observed that variations in the Evening. Primrose (Oenothera Lamarckiana) are due to mutation.

Sudden, large variations were responsible for the origin of new species.

Lamarck and Darwin believed in gradual accumulation of variations. These are the causative factors in the origin of new species.

Salient features of Mutation Theory.

Mutations or discontinuous variations are transmitted to other generations.

In naturally breeding populations, mutations occur from time to time.

No intermediate forms as they are fully fledged.

They are strictly subjected to natural selection.


26) Explain stabilizing, directional and disruptive selection with examples.

Stabilising Selection.

Operates in a stable environment.

Organisms with average phenotypes survive.

Extreme individuals from both the ends are eliminated.

No speciation.

Phenotypic stability maintained within the population over generation.

Example Measurement of sparrows that survived the storm clustered around the mean.

Sparrows that failed to survive the storm clustered around the extremes of variation. This shows stabilising selection.

Directional Selection

Gradually changing environment is subjected to the directional selection.

Individuals from one end are removed towards the other end of phenotypic distribution.

Example Size difference between the male, female sparrows.

Male and female are externally alike. They differ in body weight.

Females show directional selection in relation to body weight.

Disruptive Selection

Homogeneous environment changes into heterogeneous environment. Now this type of selection operates.

Organisms of both extreme phenotypes are selected.

Individuals with average phenotypes are eliminated.

The population is splitted into subpopulation or species.

It leads to the formation of two or more different species. It is also called adaptive radiation.

Example : The beak size of Darwin's finches in relation to seed size in Galapagos islands.


27) Rearrange the descent in human evolution

Austrolopithecus → Homo erectus → Homo sapiens → Ramapithecus → Homo habilis.


Ramapithecus → Australopithecus → Homo habilis → Home erectus → Homo sapiens.


28) Differentiate between the eating habit and brain size of Australopithecus and Ramapithecus.


29) How does Neanderthal man differ from the modern man in appearance?

Neanderthal man is different from modern man in having

Semierect posture

Flat cranium

Sloping forehead

Thin large orbits.

Heavy brow ridges.

Protruding jaws without chin.


30) Mention any three similarities found common in Neanderthal man and Homo sapiens.

Similarities between Neanderthal Man and Homo sapiens.

They know the use of fire.

They buried their dead.

Their brain capacity is more or less similar.

Brain capacity of Neanderthal man -1400 cc

Brain capacity of Homosapiens -1300 -1600 cc.


00) Define isolating mechanism and explain its types with suitable examples. 

00) Define speciation according to A.E. Emerson and explain its types giving suitable examples. 

00) Give an account on the major causes for the extinction of a particular species on earth. 

00) Explain the three level of impact of extinction of species.


31) According to Darwin, the organic evolution is due to 

a) Intraspecific competition

b) Interspecific competition

c) Competition within closely related species.

d) Reduced feeding efficiency in one species due to the presence of interfering species.

Answer: d) Reduced feeding efficiency in one species due to presence of interfering species


32) A population will not exist in Hardly-Weiberg equilibrium if 

a) Individuals mate selectively

b) There are no mutations

c) There is no migration

d) The population is large

Answer: a) Individuals mate selectively

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