CBSE Class 12 Biology Evolution Worksheet Set C

Evolution MCQ Questions with Answers Class 12 Biology

Question. Basic unit of evolution is
(a) Species
(b) Population
(c) Individual
(d) Mutation

Answer: B

Question. Which of the following is known as age of mammals
(a) Mesozoi
(b) Palaeozoic
(c) Coenozoic
(d) Archaeozoic

Answer: C

Question. The epoch of human civilization is
(a) Pliocene
(b) Holocene
(c) Pleistocene
(d) Palaeocene

Answer: C

Question.  During the origin and evolution of life, key biological compounds were progressively synthesised in ocean with the help of energy obtainable from
(a) Lightening
(b) Ultraviolet light
(c) Lightening as well as ultra-violet light
(d) Combustion of certain compounds

Answer: C

Question. The last major evolutionary advancement among the vascular plants was the emergence of flowering plants (angiosperms) about
(a) 350 million years ago
(b) 140 million years ago
(c) 16,00 million years ago
(d) 220 million years ago

Answer: B

Question.  The palaeontological evidences are obtained from
(a) Homologous structures
(b) Analogous structures
(c) Fossils
(d) Lichens

Answer: C

Question. Convergent evolution is illustrated by
(a) Rat and Dog
(b) Bacterium and Protozoan
(c) Star fish and Cuttle fish
(d) Dog fish and Whale

Answer: D

Question.  First mammals appeared around
(a) 459 million years back
(b) 220 million years back
(c) 1600 million years back
(d) 3800 million years back

Answer: B

Question. Which ones are the most essential for origin of life?
(a) Enzymes
(b) Proteins
(c) Carbohydrates
(d) Nucleic acid

Answer: D

Question. Archaeopteryx is a connecting link between
(a) Birds and reptiles
(b) Reptiles and mammals
(c) Annelids and arthropods
(d) Amphibians and fishes

Answer: A

Question. Which of the following does not illustrate the phenomenon of natural selection?
(a) Industrial melanism
(b) Herbicide resistant weeds
(c) Artificial breeding
(d) Antibiotic resistant microbes

Answer: C

Question.  Which of the following is incorrect match?
(a) Devonian period – Age of fishes
(b) Carboniferous period – Age of amphibians
(c) Ordovician period – Age of invertebrates
(d) Cretaceous period – Age of reptiles

Answer: D

Question. Ape like ancestors of human appear in epoch
(a) Pleistocene
(b) Pliocene
(c) Miocene
(d) Oligocene

Answer: B

Question. Mesozoic era is called the
(a) Age of Fishes
(b) Age of Reptiles
(c) Age of Mammals
(d) Age of Birds

Answer: B

Question. Which of the following arrangement of periods of the mesozoic era gives a correct sequence from the earliest to the latest?
(a) Jurassic, triassic, cretaceous
(b) Triassic, jurassic, cretaceous
(c) Permian, jurassic, triassic
(d) Devonian, permian, jurassic

Answer: B

Question. Evolutionary biology is the study of
(a) Civilisations
(b) History of life forms on earth
(c) Hardy-Weinberg equilibrium
(d) Reproductive success

Answer: B

Question. The flowering plants originated in which of the following periods?
(a) Cretaceous
(b) Tertiary period
(c) Triassic
(d) Carboniferous

Answer: A

Question. Which of the following is not the result of convergent evolution?
(a) Forelimbs of whales and bats
(b) Flippers of penguins and dolphins
(c) Potato and sweet potato
(d) Eye of the octopus and mammals

Answer: A

Question. The Permian period, during which the first most modern orders of insects appeared, occurred approximately
(a) 80 million years ago
(b) 150 million years ago
(c) 280 million years ago
(d) 550 million years ago

Answer: C

Question. Origin of life from nonliving matter is known as
(a) Coacervates
(b) Abiogenesis
(c) Biogenesis
(d) None of these

Answer: B

Question. Cretaceous period of the Mesozoic era is characterised by which of the following?
(a) Gymnosperms are dominant plants and first birds appear
(b) Dinosaurs become extinct and angiosperms appear
(c) Flowering plants disappear
(d) Radiation of reptiles and origin of mammal-like reptiles

Answer: B

Question. Replacement of original hard parts or even the soft tissues of the organisms by minerals is known as
(a) Compression
(b) Petrification
(c) Moulds
(d) Amber

Answer: B

Question. Which of the type of respiration probably arose first?
(a) Aerobic as it releases more energy
(b) Anaerobic as it releases more energy
(c) Aerobic as it is more complex
(d) Anaerobic as early atmosphere contained no free from of oxygen

Answer: D

Question. The study of the fossil plants is known as
(a) Palaeontology
(b) Palaeobotany
(c) Palynology
(d) Palaeoanatomy

Answer: B

Question. Which of the following is richest in fossil?
(a) Basalt
(b) Granite
(c) Lava
(d) Sedimentary rock

Answer: D

Question. Fossils of Archaeopteryx were found from
(a) Jurassic rocks
(b) Triassic rocks
(c) Cretaceous rocks
(d) Cenozoic rocks

Answer: C

Question. Which of the following can be used as an industrial pollution indicator?
(a) Lichens
(b) White-winged moths
(c) Dark-winged moths
(d) Fossils

Answer: A

Question. All the following are examples of homologous organs, except
(a) Arm of man and flipper of whale
(b) Thorn of Bougainvillaea and tendril of Cucurbita
(c) Eye of an octopus and eye of a mammal
(d) Brain of frog and man

Answer: C

Question. Amphibia first appeared in which of the following period?
(a) Permian
(b) Carboniferous
(c) Devonian
(d) Silurian

Answer: D

Question. Excreta preserved as a fossil is called as
(a) Stromatolite
(b) Compression fossil
(c) Intact fossil
(d) Coprolite

Answer: D

Question. Palaentological evidences for evolution refer to the
(a) development of embryo
(b) homologous organs
(c) fossils
(d) analogous organs.

Answer: C

Question. Stabilising selection favours
(a) both extreme forms of a trait
(b) intermediate forms of a trait
(c) environmental differences
(d) one extreme form over the other extreme form and over intermediate forms of a trait.

Answer: B

Question. Which type of selection is industrial melanism observed in moth, Biston betularia?
(a) Stabilising
(b) Directional
(c) Disruptive
(d) Artificial

Answer: B

Question. (p+q)² = p² + 2pq + q² = 1 represents an equation used in
(a) population genetics
(b) Mendelian genetics
(c) Biometrics
(d) molecular genetics.

Answer: A

Question. Appearnace of antibiotic-resistant bacteria is an example of
(a) adaptive radiation
(b) transduction
(c) pre-existing variation in the population
(d) divergent evolution.

Answer: C

Question. ‟The theory of spontaneous generation stated that
(a) life arose from living forms only
(b) life can arise from both living and non-living
(c) life can arise from non-living things only
(d) life arises spontaneously, neither from living nor from the non-living.

Answer: C

Question. Who proposed that the first form of the could have come from pre-existing non-living organic molecules?
(a) S.L. Miller
(b) Oparin and Haldane
(c) Charles Darwin
(d) Alfred Wallace

Answer: B

Question. ‟Which of the following is an example for link species?
(a) Lobe fish
(b) Dodo bird
(c) Seaweed
(d) Chimpanzee

Answer: A

Question. The bones of forelimbs of whale, bat, cheetah and man are similar in structure, because
(a) one organism has given rise to another
(b) they share a common ancestor
(c) they perform the same function.
(d) the have biochemical similarities

Answer: B

Question. One of the possible early sources of energy was/were
(a) CO₂
(b) chlorophyll
(c) green plants
(d) UV rays and lightning.

Answer: D

Question. Animal husbandry and plant breeding programmes are the examples of
(a) reverse evolution
(b) artificial selection
(c) mutation
(d) natural selection.

Answer: B

Question. Fossils are generally found in
(a) sedimentary rocks
(b) igneous rocks
(c) metamorphic rocks
(d) any type of rock.

Answer: A

Question. Abiogenesis theory of origin supports
(a) spontaneous generation
(b) origin of life from blue-green algae
(c) origin of life is due to pre-existing organisms
(d) organic evolution is due to chemical reactions.

Answer: A

Question. Analogous organs arise due to
(a) divergent evolution
(b) artificial selection
(c) genetic drift
(d) convergent evolution.

Answer: D

Question. Variations during mutations of meiotic recombination are
(a) random and directionless
(b) random and directional
(c) random and small
(d) random small and directional

Answer: A

Assertion Reason Question:

Directions: In the following questions, a statement of assertion is followed by a statement of reason.
Mark the correct choice as:
(a) Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false and Reason is true.

Question. Assertion: Wings of butterfly and bat show analogy.
Reason: Analogous organs are anatomically different but functionally similar.

Answer: A

Question. Assertion: Darwin‟s finches have different types of modified beaks according to their feeding habits.
Reason: Adaptive radiation leads to development of structures with different function arising from a common ancestor.

Answer: A

Question. Assertion: Disruptive selection changes the population into two or more groups.
Reason : This type of selection favours average sized individuals.

Answer: C

Question. Assertion: Hardy Weinberg principle explains the occurrence of variation in population and species.
Reason: It concludes that disturbances in genetic equilibrium results in evolution.

Answer: D

Question. Assertion: Theory of Biogenesis explains that life arises from pre-existing life.
Reason: Louis Pasteur finally disapproved the theory of spontaneous generation of life.

Answer: B

Question. Assertion: Among the primates, chimpanzee is the closest relative of the present-day humans.
Reason: DNA matching shows that human similarity is 100% with chimpanzee.

Answer: A

Short Answer Type Question:

Question. Consider a thorn in Bougainvillea and a tendril in Cucurbita. Are these two organs homologous or analogous? Give reason. 
Answer: Thorn in Bougainvillea and tendril in Cucurbita are homologous organs as both are stem modifications.

Question. Figures given below are of Darwin‟s finches? 
Variety of beaks of Darwin‟s finches.
(a) Mention the specific geographical area where these were found.
(b) Name and explain the phenomenon that has resulted in the evolution of such diverse species in the region.
(c) How did Darwin visit the particular geographical area?
Answer: (a) Galapagos Island.
(b) Adaptive radiation – The process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called adaptive radiation.
c) Through sea voyage in a sail ship called H.M.S Beagle.

Question. What are vestigial organs? Give examples. Write significance of vestigial organs.
Answer: Vestigial organs are non-functional organs in an organism which are functional in related animals and were functional in the ancestors. There are 90 vestigial organs in human body and mainly include coccyx (tail bone), nictitating membrane (3rd eyelid), caecum and vermiform appendix, canines, wisdom teeth, body hair, auricular muscles. Vestigial organs are also present in some other animals eg:
splint bones in horse, hindlimbs and pelvic girdles in python, wings and feathers in flightless birds etc.
Significance of vestigial organs:
(I) Vestigial organs were functional in the ancestral forms but have become nonfunctional due to changes in their function and may finally disappear. So, the presence of vestigial organs is convincing evidence of organic evolution and is supported by Lamarck‟s Theory of use and disuse of organs.

Question. Why are wings of a butterfly and of a bat called analogous? 
Answer: They are analogous organs due to the fact that the basic structure of wing of insects is different from the wings of a bird. However, their function is similar. Analogous organs are result of convergent evolution.

Question. Explain how natural selection has worked on population of peppered moth in industrial area of England. 
Answer: Industrial melanism: It is an example of natural selection shown by peppered moth Biston betularia. The moth had a dull grey coloured body before industrial revolution in England. The colour of moth enabled it to adapt to the light-coloured background. After the industrial revolution the environment changed with the deposition of tar soot. As a result, light coloured species of moth disappeared but a new black coloured moth Biston carbonaria a dominant mutant appeared within a couple of hundred years. The change enabled the animal to adjust with the changed environment.
However, with the replacement of coal and petroleum by gas and electricity the situation has changed once again and the grey form has become abundant with a sharp decline in the number of black. The reason being the decrease in pollution and restoration of grey colour of the lichens on the tree trunk which provide safety to the grey form and exposes the black one to predator. Thus industrial melanism is an interesting example of evidence in favour of natural selection.

Question. Stanley Miller and Harold Urey performed an experiment by recreating in the laboratory the probable conditions of the atmosphere of the primitive earth.
(i) What was the aim of the experiment?
(ii) In what forms was the energy supplied for chemical reactions to occur?
(III) For how long was the experiment run continuously? Name two products formed.
Answer: (i) To prove Oparin‟s theory of origin of life.
(ii) Electric discharge using electrodes.
(iii) One week; Amino acids and Sugar.

Question. Evolution is the change of gene frequencies in a population in response to changes in environment in the time scale of years and not centuries. Justify the statement with reference to DDT. How does the theory of Hugo de varies support this? 
Answer: As the environment changes the organism which are better adapted to the changed environment could survive better and reproduce.
- When DDT was used, initially most of the mosquitoes died, but a few survived.
-These few mosquitoes reproduce and their off springs were also resistant to DDT.
- Today, the population of mosquitoes mostly contains DDT resistance mosquitoes.
- The DDT resistant mosquitoes have evolved in a time scale of years or months and not centuries.
- So, evolution is a direct process but stochastic process based on chance mutation and chance events.
- According to Hugo de Varies, evolution occurs due to mutations. Large differences arising suddenly in a population.
- According to him large, single-step mutation, called saltation, must have been the cause of DDT- resistance in mosquitoes.

Question. Why is Archaeopteryx called a connecting link between reptiles and birds? 
Answer: Archaeopteryx is a bird as it has feathers and a beak. But like reptiles it has a long tail, jaws full of teeth claws on fore fingers and keelless sternum. Thus it represents a stage between reptiles and birds through Archaeopteryx like intermediate form.

Question. How did Darwin theory of natural selection explain the appearance of new forms on the earth? 
Answer: Darwin's theory of Natural selection:
Any population has built in variation for every character.
Individuals with those characters which enable them to survive better would outbreed the others, who are less adapted.
Fitness, according to Darwin's is reproductive fitness, i.e., individuals who are better fit in an environment leaves more progeny than others.
These progenies now comes to possess more fit individuals, i.e., nature selects the better fit individuals and over a long period of time, through a number of generations, the population slowly becomes modified into a different form, or a species, which is called evolution.

Question. State and explain any three factors affecting allele frequency in populations.
Answer: 1. Gene migration or gene flow – it is the movement of alleles into a gene pool or out of a gene pool.
2. Genetic drift – If the movement of alleles into a gene pool or out of a gene pool takes place by chance is called Genetic Drift.
3. Mutation – It is the large difference arising suddenly in a population, they are random and occur in all directions.

Question. How is artificial selection different from natural selection? 
Answer: 

Question. You have studied the story of Pepper moths in England. Had the industries been removed, what impact could it have on the moth population? 
Answer: The story of Pepper moths in England happened because, in the post industrialisation period, the lichens did not survive due to increased pollution. Soot covered the tree trunks making them dark.
Now, had the industries be removed, the pollution level would have gone down, allowing lichen to grow back and the number of white-winged moths would have gone up again.

Question. Classify the following as examples of homology and analogy–
(i) Hearts of fish and crocodile
(ii) Wings of butterfly and birds
(iii) Eyes of Octopus and Mammals
(iv) Tubers of potato and sweet potato
(v) Thorns of Bougainvillea and spines of Opuntia
(vi) Thorn of Bougainvillea and tendrils of cucurbits.
Answer: (i) Homology (ii) Analogy (iii) Analogy (iv) Analogy (v) Analogy (vi) Homology

Question. Define genetic drift. How does it produce founder effect and genetic bottleneck?
Answer: Random change occurring in the allele frequency by chance alone are called genetic drift.
Founder effect: When a population gets separated from the existing population, it becomes founder of new population. This is called the founder effect which is the result of genetic drift ie by chance.
Genetic bottle neck: When in a season the one population died leaving few individuals of the population which become the founder of new population then it will produce only few genes by selection only ie by chance new population is emerged and it is similar to a bottle in which only certain population is allowed to flow as in neck of bottle.

Question. State the theory of abiogenesis. How does miller's experiment support this theory? 
Answer: Theory of chemical evolution of abiogenesis was proposed by Operon and Haldane.
It states that the first form of life could have come from pre-existing non-living organic molecules like RNA's etc., and that and that formation of life was preceded by chemical
evolution, i.e. Formation of diverse organic molecules from in organic constituents.

Long Answer Type Question:

Question. Study of light & dark winged moths in England between1850 to 1920 revealed a phenomenon.
a. Name the phenomenon.
b. What statistics regarding the number of moths was observed? Compare.
c. What explanation was given for these observations?
d. List another characteristic example of evolution by anthropogenic action.
Answer: a. Industrial melanism
b. Lighter moths were more in number in the pre industrial revolution period & melanic moths were more in the post-industrial revolution period
c. During the pre –industrial period, there was hardly any air pollution, lichens thrived & light winged moths were not spotted by predators & they survived.
d. In the post industrialization period, pollution increased, carbon particles were deposited on tree trunks & the white moths were easily spotted by their predators & hence their numbers decreased
e. Use of pesticides that led to the evolution of resistant varieties of insect pests Use of antibiotics that led to the evolution of resistant bacteria

Question. Based on the experiment conducted by Miller in 1953 , answer the following questions:
a. Which gases were used in the experiment?
b. What was the purpose of the electrodes in the flask?
c. What was their observation?
d. What did they conclude?
Answer: a. gases used were methane, ammonia, hydrogen & water vapour
b. electrodes were used to produce electric discharge, similar to the lightening that occurred on primitive earth, which provided energy for chemical evolution on earth.
c. They observed the formation of biomolecules like amino acids
d. They concluded that the first forms of life arose slowly through evolutionary forces from non – living molecules.

Question. How does Hardy –Weinberg equation explain genetic equilibrium? Describe how this equilibrium gets disturbed leading to founder effect?
Answer: The Hardy-Weinberg equilibrium is a principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.
The Hardy-Weinberg equation used to determine genotype frequencies is: p² + 2pq + q² = 1. Where 'p²' represents the frequency of the homozygous dominant genotype (AA), '2pq' the frequency of the heterozygous genotype (Aa) and 'q2' the frequency of the homozygous recessive genotype (aa). The conditions to maintain the Hardy-Weinberg equilibrium are: no mutation, no gene flow, large population size, random mating, and no natural selection. The Hardy-Weinberg equilibrium can be disrupted by deviations from any of its five main underlying conditions The equilibrium gets disturbed due to genetic drift which refers to the changes in allele frequencies of a population occurring by chance. The change in allele frequency may be so different that the population becomes a different species, the original population becomes founders and such an effect is called founder effect

Diagram Based Questions:
 

Question. Study the diagram and comment upon the theory of evolution that is illustrated here.

Answer: The diagram illustrates the theory of inheritance of acquired characteristics, commonly referred to as Lamarckism as it was suggested by the naturalist, Jean Lamarck. This idea states that modifications in an individual are caused by its environment, or the use or disuse of a structure during its lifetime, and that these changes can be inherited by its offspring, bringing about change in a species. According to Lamarckism, the ancestors of giraffe had small neck and forelimbs. They were residing in places with no surface vegetation, therefore, they had to stretch their neck and forelimbs to take the leaves for food.
The longnecked giraffes evolved because of stretching of necks over many generations by short necked giraffes.

1. Observe the given diagram and answer the questions. 

Question. Write on the conclusion of this experiment. 
Answer: The experiment proves some of the steps suggested by chemical evolution theory of Oparin and Haldane. The formation of organic compounds from primitive gases was proved in the experiment.

Question. Label the gases marked as a,b,c and d.
Answer: a. CH4 b. NH3 c.H2O d. H2 (The order of gases may interchange)

Question. Mention the nature of the content marked as E
Answer: E is the condensed liquid which contains organic molecules like amino acids.

Question. The picture is a representation of adaptive radiation of marsupials in Australia.
What is meant by adaptive radiation? Cite any other example for the same 

Answer: Adaptive radiation is the rapid diversification of a single species into many species that inhabit a variety of environments or use a variety of resources. Evolution of placentals in Australia, evolution of Darwin finches is also considered as examples for adaptive radiation.

Question. Australian marsupials and placentals show remarkable similarity in their appearance. What is the evolutionary significance of this similarity? Explain.

Answer: The diagram represents convergent evolution of Australian marsupials and Australian placentals.
The independent evolution of Australian marsupials is an example of adaptive radiation. Evolution of Australian placentals also considered as an example for adaptive radiation. If more than one adaptive radiation takes place in an isolated geographic area, it is considered as an example of convergent evolution. Convergent evolution is the independent evolution of similar features or traits in unrelated species to suit with similar environmental needs.

Question. Observe the forelimbs in the following animals. What kind of organs they represent, in evolutionary context? What kind of evolution resulted in these organs? 

Answer: These organs represent Homologous organs. Homologous organs are organs with same basic structure and origin but different appearance and function. All these organs have same kind of bones like humerus, radius, ulna, carpals, metacarpals and phalanges but have different appearance due to different functions they perform. Homologous organs are resulted from divergent evolution.

Question. Observe the given diagram. Explain the evolutionary process which is considered as a classic example of natural selection 

Answer: The diagram is a representation of Industrial melanism which is considered as a classic example of evolution by natural selection. It explains the evolution of dark coloured body by some organisms in response to the pollution caused by industrialization. The black-coloured body was selected by nature as it was easily blending with the dark background caused by excessive carbon emission from various industries.

Question. The given picture is a representation of three types of natural selection. Observe the figures 1,2 and 3 and explain the type of natural selection they represent. 

Answer: The diagram is a representation of three types of natural selection.
1. Stabilizing selection.: a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value. If natural selection favours an average phenotype by selecting against extreme variation, the population will undergo stabilizing selection.
2. Directional selection. a mode of natural selection in which a single phenotype is favoured, causing the allele frequency to continuously shift in one direction. When the environment changes, populations will often undergo directional selection, which selects for phenotypes at one end of the spectrum of existing variation.
3. Disruptive / Diversifying selection. Both extreme phenotypes are more fit than those in the intermediate phenotypes. Sometimes natural selection can select for two or more distinct phenotypes that each have their advantages. This type of selection often drives speciation.

Question. The picture represents a factor which can affect Hardy- Weinberg equilibrium. Name and explain the evolutionary process? 

Answer: The diagram represents Genetic drift. Genetic drift is the change in the frequency of an allele in a population due to random sampling (random selection). Genetic drift occurs in all populations but its effects are strongest in small populations. Genetic drift includes the founder effect. The founder effect occurs when a portion of the population (i.e., “founders”) separates from the old population to start a new population with different allele frequencies

Question. The picture represents the observation of Darwin in Galapagos Island. What did he observe in these birds? What was the conclusion from his observation? 

Answer: These birds are Darwin‟s finches. Darwin observed that there were many varieties of finches in the same island. All the varieties he came across had evolved on the island itself. They were originally adapted with seed-eating features. From these many other forms evolved with altered beaks depending on the food habit. This enabled them to become insectivorous, vegetarian finches etc. The evolution of Darwin‟s finches is considered as an example for adaptive radiation. The observation also helped Darwin to form his theory of natural selection.

More Question

1. Who proposed the theory of chemical origin of life?

2. What provided energy for abiodic synthesis on primitive earth?

3. Name 2 scientists who set up a special expt. To prove oparin’s theory of origin of life.

4. What is fitness according to Darwin?

5. Bring out the difference between de vries mutations and Darwinian variations.

6. Describe the theory of Biogenesis

7. What are the different ways in which natural selection along with reproductive success results in different populations.

8. State Hardy-Weinberg principle.

9. What is adaptive radiation. Give 2 examples.

10. Explain industrial melanism

11. Trace the evolution of man

12. Name the 6 groups of plants for which Psilophyton was the ancestor.

13. Give 2 examples of evolution dur to anthropogenic action.

14. What is founder effect?

15. How does gene migration and recombination affect Hardy-Weinberg equilibrium?

16. What is genetic drift?

17. Give examples of homologous and analogous organs (in plants and animals)

18. Explain the evolution of earth and first life forms.

19. Who proposed the cosmozoan theory?

20. Name the immediate ancestor of bryophytes.

21. What is the significance of Archaeopteryx?

22. Name the primates that existed 15 mya

23. What does homology and analogy indicate?

24. Name the period in the geological history when reptiles flourished