Solution- Evolution Test-3 Class 12 Notes | EduRev

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Class 12 : Solution- Evolution Test-3 Class 12 Notes | EduRev

 Page 1


CBSE TEST PAPER-10 
CLASS - XII BIOLOGY (Evolution)
[ANSWERS] 
Ans 1. Very high temperature due to lightening or uv – rays provided energy for a biotic 
synthesis. 
Ans 2. Louis Pasteur 
Ans 3. Gene pool refers to sum total of different kinds of genes pooled by all the members 
of a population. 
Ans 4. Since this fossil bird has both avian characters & reptilian characters e.g. scales on 
body & teeth in beak it would be considered as a connecting link between reptiles 
& bird. 
Ans 5. Speciation refers to the origin of new species or the phenomena of development of 
new species from pre-existing one.  
The two factors which lead to speciation are – Genetic drift, mutation & natural 
selection.   
Ans 6. Wings of butterfly & bat are said to be analogous because they have originated 
from different parts – e.g. in butterfly wings are originated from skin and feather & 
in bats wings are originated from forelimbs but both of them performs the same 
function of flying. 
Ans 7. Natural selection is a process of selection lay nature in which individuals with 
those characteristics which enable them to survive better in natural conditions 
would outnumber the others who are less adapted under the same natural 
conditions  
Page 2


CBSE TEST PAPER-10 
CLASS - XII BIOLOGY (Evolution)
[ANSWERS] 
Ans 1. Very high temperature due to lightening or uv – rays provided energy for a biotic 
synthesis. 
Ans 2. Louis Pasteur 
Ans 3. Gene pool refers to sum total of different kinds of genes pooled by all the members 
of a population. 
Ans 4. Since this fossil bird has both avian characters & reptilian characters e.g. scales on 
body & teeth in beak it would be considered as a connecting link between reptiles 
& bird. 
Ans 5. Speciation refers to the origin of new species or the phenomena of development of 
new species from pre-existing one.  
The two factors which lead to speciation are – Genetic drift, mutation & natural 
selection.   
Ans 6. Wings of butterfly & bat are said to be analogous because they have originated 
from different parts – e.g. in butterfly wings are originated from skin and feather & 
in bats wings are originated from forelimbs but both of them performs the same 
function of flying. 
Ans 7. Natural selection is a process of selection lay nature in which individuals with 
those characteristics which enable them to survive better in natural conditions 
would outnumber the others who are less adapted under the same natural 
conditions  
Alfred Wallace also proposed the same mechanism of evolution & called it 
“survival of fittest”.   
Ans 8. The following facts that supports Darwin’s theory of Natural selection 
i) Overproduction: - All organisms tend to multiply at high rate but it is not
possible for all organisms to survive.
ii) Struggle for Existence: - Because of limitation of space & food all the offspring
of the result of overproduction will not survive & they will compete with one
another to grow this develops struggle for existence not only among
individuals of different species but also among same species.
iii) Variations :- No two individuals of same species are exactly alike even coming
out from same parent al stock.
iv) Survival of fittest :- The individuals with useful variation will survive during
struggle of existence while those with less fortunate variation would perish.
Ans 9. The common ancestor of apes & man is a primate Dryopithecus that lived about 15 
million years ago the human evolution is as follows :-  
a) Australopithecus :- They are 4ft, with brain capacity – 500 to 650 cc. They have
bipedal locomotion, omnivorous & has erect posture. They hunted with stone
weapon & lived in caves.
b) Homo Erectus :- They showed increase in brain size They are good hunters, ate
meat domesticate animal & discover fire.
c) Netherlands man :- They were short with heavy brows retreating forehead
large jaws & stooped postures They wore clothes, good hunters & tool makers.
d) Cromagnon man :- They were completely erect & 6ft tall. He used bones as
tools & was a cave dweller. They are excellent tool makers & fine artists.
e) Homo sapiens :- They have brain capacity 1450cc. & skull much thicker. His
intelligence has enabled him to adapt & control environment. He started
agriculture.
Page 3


CBSE TEST PAPER-10 
CLASS - XII BIOLOGY (Evolution)
[ANSWERS] 
Ans 1. Very high temperature due to lightening or uv – rays provided energy for a biotic 
synthesis. 
Ans 2. Louis Pasteur 
Ans 3. Gene pool refers to sum total of different kinds of genes pooled by all the members 
of a population. 
Ans 4. Since this fossil bird has both avian characters & reptilian characters e.g. scales on 
body & teeth in beak it would be considered as a connecting link between reptiles 
& bird. 
Ans 5. Speciation refers to the origin of new species or the phenomena of development of 
new species from pre-existing one.  
The two factors which lead to speciation are – Genetic drift, mutation & natural 
selection.   
Ans 6. Wings of butterfly & bat are said to be analogous because they have originated 
from different parts – e.g. in butterfly wings are originated from skin and feather & 
in bats wings are originated from forelimbs but both of them performs the same 
function of flying. 
Ans 7. Natural selection is a process of selection lay nature in which individuals with 
those characteristics which enable them to survive better in natural conditions 
would outnumber the others who are less adapted under the same natural 
conditions  
Alfred Wallace also proposed the same mechanism of evolution & called it 
“survival of fittest”.   
Ans 8. The following facts that supports Darwin’s theory of Natural selection 
i) Overproduction: - All organisms tend to multiply at high rate but it is not
possible for all organisms to survive.
ii) Struggle for Existence: - Because of limitation of space & food all the offspring
of the result of overproduction will not survive & they will compete with one
another to grow this develops struggle for existence not only among
individuals of different species but also among same species.
iii) Variations :- No two individuals of same species are exactly alike even coming
out from same parent al stock.
iv) Survival of fittest :- The individuals with useful variation will survive during
struggle of existence while those with less fortunate variation would perish.
Ans 9. The common ancestor of apes & man is a primate Dryopithecus that lived about 15 
million years ago the human evolution is as follows :-  
a) Australopithecus :- They are 4ft, with brain capacity – 500 to 650 cc. They have
bipedal locomotion, omnivorous & has erect posture. They hunted with stone
weapon & lived in caves.
b) Homo Erectus :- They showed increase in brain size They are good hunters, ate
meat domesticate animal & discover fire.
c) Netherlands man :- They were short with heavy brows retreating forehead
large jaws & stooped postures They wore clothes, good hunters & tool makers.
d) Cromagnon man :- They were completely erect & 6ft tall. He used bones as
tools & was a cave dweller. They are excellent tool makers & fine artists.
e) Homo sapiens :- They have brain capacity 1450cc. & skull much thicker. His
intelligence has enabled him to adapt & control environment. He started
agriculture.
Ans 10.  The three different ways in which selection may occur are as below:- 
i) Stablising Selection :- Individuals with intermediate value of heritable
phenotypic characteristics are favoured over other individuals.
ii) Directional Selection :- Individuals with one extreme of heritable phenotypic
characteristic have an advantage over individuals in a population.
iii) Disruptive Selection :- individuals with either of both extreme of heritable
phenotypic characteristics have advantage over individuals with intermediate
phenotype.
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