Class 12 Biology MCQs Chapter – 7
21. It is beleived that earth’s atmosphere before origin of life was consisted of a mixture of :
( A ) CH4, O3 , O2 , NH3
( B ) CH4,NH3, H2, H2O vapours
( C ) CH4 , NH3, CO2, H2
( D ) H2, CO2, H2O, NH2
Answer-( B )
22. The primate which existed 15 mya was
( A ) Homohabilis
( B ) Australopithecus
( C ) Ramapithecus
( D ) Homo errectus
Answer-( C )
23. Which is an example of homology ?
( A ) Eye of octopus and mammals
( B ) Wings of butterfly and birds
( C ) Flippers of penguins and dolphins
( D ) Thorns of Boughainvillea and tendrils of cucurbits
Answer-( D )
24. The brain capacity of Homo erectus was about :
( A ) 650 C.C.
( B ) 900 C.C.
( C ) 1500 C.C.
( D ) 1200 C.C.
Answer-( B )
25. The prebiotic atmosphere of earth was of a reducing nature. It was transformed into an oxidizing atmosphere of present day due to the emergence of:
( A ) Cyanobacteria
( B ) angiosperms
( C ) photosynthetic bacteria
( D) eukaryotic algae
Answer-( A )
26. Non directional alteration in Hardy-Weinberg equilibrium is :
( A ) Gene flow
( B ) Mutation
( C ) Genetic drift
( D ) Gene recombination.
Answer-( C )
27. A gene of operon which forms the repressor protein is :
( A ) Operator
( B ) Promoter
( C ) Regulator
( D ) Structural
Answer-( C )
28. Which one is linked to evolution ?
( A ) Extinction
( B ) Variation
( C ) Reproduction
( D ) Competition
Answer-( B )
29. Dodo is-
( A ) Extinct species
( B ) Endangered species
( C ) Threatened species
( D) All of these
Answer-( A )
30. The earliest hominids evolved about 4 million years ago were :
( A ) Homo erectus
( B ) Neanderthal man
( C ) Cro Magnon man
( D ) Australopithicus
Answer-( D )
31. The first cellular form of life possibly came into existence in :
( A ) 2000 million
( B ) 2000 billion
( C ) 4500 million
( D ) 4.5 billion
Answer-( A )
32. Sweet potato and Potato represent:
( A ) analogous structure
( B ) Divergent evolution
( C ) belong to same ganes
( D) both A & C
Answer-( A )
33. The extinct human ancestor who ate only fruits and hunted with stone weapons was-
( A ) Ramapithecus
( B ) Australopithecus
( C ) Dryopithecus
( D ) Homo errectus
Answer-( B )
34. The most apparent change during the evolutionary history of Homosapiens is traced in :
( A ) Loss of body hair
( B ) walking upright
( C ) shortening of jaws
( D ) remarkable increase in brain size
Answer-( D )
35. The devonian period is considered as
( A ) age of fishes
( B ) age of amphibians
( C ) age of reptiles
( D ) age of mammals
Answer-( A )
36. First life formed on earth was a
( A ) cyanobacterium
( B ) chemoheterotroph
( C ) autotroph
( D ) photoautotroph
Answer-( B )
37. The presence of gillslits in the embryo of all vertebrates, supports the theory of :
( A ) metamorphosis
( B ) biogenesis
( C ) organic evolution
( D ) recapitulation
Answer-( D )
38. phenomenon of ‘industrial melanism demonstrates :
( A ) geographical isolation
( B ) reproductive isolation
( C ) natural selection
( D ) induced mutation
Answer-( C )
39. Which is not a vestigeal organ in man ?
( A ) Nictiating membrane
( B ) Tail vertebrae
( c ) Vermiform appendix
( D ) Nails
Answer-( D )
