Saturday, January 2, 2021

Evolution | Class 12 Zoology | Previous Years Questions and Answers (2018 to 2020)

 5. EVOLUTION


2020 SAY


1.   Which among the following is an example for homology? (1)

(a)    The eye of the Octopus and of Mammals

(b)   Sweet potato and potato

(c)    Thorns and tendrils of Bougainvillea and Cucurbita

(d)   Wings of butterfly and of birds


ü Answer:

(c) Thorns and tendrils of Bougainvillea and Cucurbita.

2.   (a) Define Hardy – Weinberg principle.

(b) List out any two factors affecting Hardy – Weinberg Equilibrium. (2)

ü Answer:

(a) Allele frequencies in a population are stable and is constant from generation to generation.

(b) Gene migration, Genetic drift, Mutation etc.

3.   Diagrammatic representation of the operation of natural selection on different traits is shown below: (2)

I.   Identify ‘a’, ‘b’ and ‘c’.

II.  What is the evolutionary significance of ‘b’?


ü Answer:

                 I.  a. Stabilizing selection.

b. Directional selection.

c. Disruptive selection.

                II.  The peak is shifted to one direction. i.e., more individuals acquire value other than the mean character value.


2020 MARCH

1.     Which of the following human ancestor is more ‘ape’ like? (1)

a.      Homo habilis                           

b.     Dryopithecus

c.      Australopithecines                  

d.     Homo erectus

ü Answer:

(b) Dryopithecus

2.     Fill the blanks in Column A and B using appropriate terms. (2)

Theory

Scientists

(a)    Theory of natural selection

A

(b)   Use and disuse of organs

B

(c)    Theory of mutation

C

(d)   Theory of spontaneous generation

D

ü Answer:

A= Charles Darwin

B= Lamarck

C= de Vries

D= Aristotle / Louis Pasteur.

3.     p2 + 2pq + q2 = 1 denotes an evolutionary principle. (2)

a.      Name the principle.

b.     Mention any three factors affecting this.

ü Answer:

(a) Hardy – Weinberg Principle.

(b) Gene migration, Genetic drift, Mutation etc.

2019 SAY June

1.   Based on evolution in the geological period arrange the plants and animals in the correct order in various million years ago. Choose the appropriate organisms from the bracket. (2)

[Reptiles, Plants, Sea-weeds, Jawless fish, Fish with stout fin]

ü Answer:

(a) 500 mya: Plants.

(b) 350 mya: Jawless fishes, fish with stout fins.

(c) 320 mya: Sea-weeds. Plants.

(d) 200 mya: Reptiles

2.  Make a flow chart using the following terms: (2)

[Natural selection, Struggle for existence, Variation, Origin of species, Over production, Survival of the fittest]

ü Answer:

Over production → Struggle for existence → Variation → Survival of the fittest → Natural selection → Origin of species.

2019 MARCH


1.   Prepare a flow chart showing the evolution of modern man in the hierarchical order of their evolution using the details given below: (2)


Homo erectus, Homo habilis, Dryopithecus, Australopithecines, Homo sapiens, Ramapithecus, Neanderthal man


ü Answer:


Dryopithecus → Ramapithecus → Australopithecines → Homo habilis → Homo erectus → Neanderthal man → Homo sapiens     


2.   Some examples of evolutionary structures are given below. Classify them under suitable headings: (2)

a.  Forelimb of Man, Cheetah, Whale, Bat.

b.  Wings of Butterfly, Bird.

c.  Thorns and tendrils of Bougainvillea and Cucurbita.

d.  Vertebrate hearts or brains.

e.  Eye of the Octopus and Mammals.

f.   Flippers of Penguins and Dolphins.


ü Answer:


Homologous organs:

a.   Forelimb of Man, Cheetah, Whale, Bat.

b.   Thorns and tendrils of Bougainvillea and Cucurbita.

c.    Vertebrate hearts or brains.

Analogous organs:

·     Wings of Butterfly, Bird.

·     Eye of the Octopus and Mammals.

·     Flippers of Penguins and Dolphins.


2018 SAY


1.   p2 + 2pq + q2 = 1 is the gene frequency of a population showing an evolutionary principle. (2)

a.      Name the principle.

b.     Enlist any three factors affecting this principle.


ü Answer:


(a) Hardy-Weinberg principle.

(b) Gene migration, Genetic drift, Natural selection etc.


2.  Above homologous organs provide evidence for a particular type of evolution. (2)



a.      Identify the type of evolution.

b.     What do you mean by homologous organs?


ü Answer:

(a) Divergent evolution.

(b) Homologous organs are the organs having fundamentally similar structure and origin but different functions.


3.   Prepare a flowchart of evolution of man in descending order by choosing the names given below: (3)

Homo sapiens, Homo erectus. Homo habilis, Austrapithecines, Ramapithicus, Neanderthal


ü Answer:


Ramapithecus → Austrapithecines → Homo habilis → Homo erectus → Neanderthal → Homo sapiens.


2018 MARCH


1.   Complete the boxes with the suitable words given below: (2)

[Analogues, Homologues, Convergent evolution, Divergent evolution]



ü Answer:


A= Homologous organs.

B= Divergent evolution.

C= Analogous organs.

D= Convergent evolution


2.   Explain the factors affecting the Hardy-Weinberg equilibrium. (2)


ü Answer:


Gene migration, Genetic drift, Mutation, Genetic recombination, Natural selection.



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