Solution- Evolution Test-1 Class 12 Notes | EduRev

Class 12 : Solution- Evolution Test-1 Class 12 Notes | EduRev

 Page 1


CBSE TEST PAPER-08 
CLASS - XII BIOLOGY (Evolution)
[ANSWERS] 
Ans 1. Vermiform appendix, wisdom teeth. 
Ans 2. Mutations. 
Ans 3. Genetic Drift. 
Ans 4. Homologous organs are those organs which are similar in basic structure & 
embryonic developments but perform different functions. e.g. bones of forelimbs 
of whales, bat, birds and human beings.     
Ans 5. Variations are useful for survival of species in changed environmental situations. If 
a population of reproducing organisms are suited to a particular niche & if the 
niche is drastically altered the population could be wiped out however if some 
variations were to be present in few individuals, there would be some chances for 
them to survive. 
Ans 6. Missing link between birds & reptiles called. Archaeopteryx showed that “Birds 
have evolved from reptiles”. These are organisms which show the characters of 
both birds (e.g. presence of wings & feathers in the body) as well as of reptiles (e.g. 
gong tail & jaws with identical teeth).     
Ans 7. Theory of natural selection states that due to survival of fittest, the species change 
readily owing to preservation & transmission of minute variation & gradually give 
rise to new forms.  
Example – In collection of moths in 1850 it was observed that there were whiter 
winged moth than dark winged but after industrialization there were darker 
wringed moth. This is due to the reason that During post industrial period trees 
trunk become dark due to industrial smoke under this condition, white winged 
Page 2


CBSE TEST PAPER-08 
CLASS - XII BIOLOGY (Evolution)
[ANSWERS] 
Ans 1. Vermiform appendix, wisdom teeth. 
Ans 2. Mutations. 
Ans 3. Genetic Drift. 
Ans 4. Homologous organs are those organs which are similar in basic structure & 
embryonic developments but perform different functions. e.g. bones of forelimbs 
of whales, bat, birds and human beings.     
Ans 5. Variations are useful for survival of species in changed environmental situations. If 
a population of reproducing organisms are suited to a particular niche & if the 
niche is drastically altered the population could be wiped out however if some 
variations were to be present in few individuals, there would be some chances for 
them to survive. 
Ans 6. Missing link between birds & reptiles called. Archaeopteryx showed that “Birds 
have evolved from reptiles”. These are organisms which show the characters of 
both birds (e.g. presence of wings & feathers in the body) as well as of reptiles (e.g. 
gong tail & jaws with identical teeth).     
Ans 7. Theory of natural selection states that due to survival of fittest, the species change 
readily owing to preservation & transmission of minute variation & gradually give 
rise to new forms.  
Example – In collection of moths in 1850 it was observed that there were whiter 
winged moth than dark winged but after industrialization there were darker 
wringed moth. This is due to the reason that During post industrial period trees 
trunk become dark due to industrial smoke under this condition, white winged 
moth do not survive due to predators dark winged moth survived Before 
industrialization sets in, thick growth off white colored lichen covered trees in that 
background white winged moth survived but dark – colored moth were picked out 
by predators hence nature selects which species is suitable. 
Ans 8. Urey & miller tried to create in the laboratory the similar conditions which might 
have existed in early primitive atmosphere. A mixture of water vapours methane, 
ammonia & hydrogen is exposed to electric discharge in a closed chamber, this 
fluid thus formed is allowed 
to stand for several week as 
a result, amino acids e.g. 
glycerine & alanine are 
formed from fluid. They 
suggested that electric 
discharge produced during 
lightening in primitive 
atmosphere of earth might 
have resulted in formation 
of organic compound. 
Ans 9. According to Oparin & Haldane’s Biochemical origin of life; origin of life occurs in 
three stages  
1 CHEMOGENY / CHEMICAL EVOLUTION :- Acc to them most of the primitive 
form of life would have generated spontaneously from some inorganic matter 
as a result of action of special external forces e.g. electric charge, uv-light etc.  
i) Many saturated & unsaturated hydrocarbons were feasted when temp
cooled to 90
0 
 c or below.
ii) From hydrocarbons small chain compounds of C, H, O are formed which
condense to form sugar.
Page 3


CBSE TEST PAPER-08 
CLASS - XII BIOLOGY (Evolution)
[ANSWERS] 
Ans 1. Vermiform appendix, wisdom teeth. 
Ans 2. Mutations. 
Ans 3. Genetic Drift. 
Ans 4. Homologous organs are those organs which are similar in basic structure & 
embryonic developments but perform different functions. e.g. bones of forelimbs 
of whales, bat, birds and human beings.     
Ans 5. Variations are useful for survival of species in changed environmental situations. If 
a population of reproducing organisms are suited to a particular niche & if the 
niche is drastically altered the population could be wiped out however if some 
variations were to be present in few individuals, there would be some chances for 
them to survive. 
Ans 6. Missing link between birds & reptiles called. Archaeopteryx showed that “Birds 
have evolved from reptiles”. These are organisms which show the characters of 
both birds (e.g. presence of wings & feathers in the body) as well as of reptiles (e.g. 
gong tail & jaws with identical teeth).     
Ans 7. Theory of natural selection states that due to survival of fittest, the species change 
readily owing to preservation & transmission of minute variation & gradually give 
rise to new forms.  
Example – In collection of moths in 1850 it was observed that there were whiter 
winged moth than dark winged but after industrialization there were darker 
wringed moth. This is due to the reason that During post industrial period trees 
trunk become dark due to industrial smoke under this condition, white winged 
moth do not survive due to predators dark winged moth survived Before 
industrialization sets in, thick growth off white colored lichen covered trees in that 
background white winged moth survived but dark – colored moth were picked out 
by predators hence nature selects which species is suitable. 
Ans 8. Urey & miller tried to create in the laboratory the similar conditions which might 
have existed in early primitive atmosphere. A mixture of water vapours methane, 
ammonia & hydrogen is exposed to electric discharge in a closed chamber, this 
fluid thus formed is allowed 
to stand for several week as 
a result, amino acids e.g. 
glycerine & alanine are 
formed from fluid. They 
suggested that electric 
discharge produced during 
lightening in primitive 
atmosphere of earth might 
have resulted in formation 
of organic compound. 
Ans 9. According to Oparin & Haldane’s Biochemical origin of life; origin of life occurs in 
three stages  
1 CHEMOGENY / CHEMICAL EVOLUTION :- Acc to them most of the primitive 
form of life would have generated spontaneously from some inorganic matter 
as a result of action of special external forces e.g. electric charge, uv-light etc.  
i) Many saturated & unsaturated hydrocarbons were feasted when temp
cooled to 90
0 
 c or below.
ii) From hydrocarbons small chain compounds of C, H, O are formed which
condense to form sugar.
iii) Ketones & aldehydes condenses & polymerises to form fatty acid.
iv) Ammonia, hydrocarbon & H 2 O reacted together to form amino acid.
v) Hot sea water which was rich in primary organic compound reacted to
form nucleotides.
2) BIOGENY / BIOLOGICAL EVOLUTION :- This stage consists of
i) Formation of nucleic acids by polymerization of nucleotide.
ii) Giant molecules of nucleoproteins have a tendency to be aggregated in
various combinations to form large colloidal particles called
COACERVATES.
iii) The development of plasma membrane resulted in accumulation of
different substances inside coacervates & occurrence of certain internal
reaction lad to development of cell.
3) Cognogeny :- Cognogeny involves differentiation or diversification of living
beings from simplest first living cell. The first organism evolved was chemo- 
autotrophic bacteria which later converted to tree autotrophic bacteria e.g.
green algae.
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