Class 12 Biology MCQs Chapter – 5
21. The trisomy of 21st chromosome causes
( A ) Kleinfelter’s syndrome
( B ) Turner’s Syndrome
( C ) Sickle cell Anemia
( D ) Down’s syndrome
ANS-( D )
22. ABO blood grouping in human beings cites the examples of
( A ) Incomplete dominance
( B ) Co – dominance
( C ) Multiple allelism
( D ) Both ( B ) and ( C )
ANS-( D )
23. Which of the following will not result in variation among siblings ?
( A ) Independent assortment
( B ) Crossing over
( C ) Linkage
( D ) Mutation
ANS-( C )
24. Chromosomal theory of inheritance was given by :
( A ) Morgan
( B ) Sutton & Boveri
( C ) Hugo de Vries
( D ) Mendel
ANS-( B )
25. Which of the following is not an example of recessive autosomal disease ?
( A ) Haemophilia
( B ) Cystic Fibrosis
( C ) Phenylketonuria
( D ) Sickle-cell Anemia
ANS-( A )
26. Mongolism in a genetic disorder caused by the presence of an extra chromosome number:
( A ) 20
( B ) 21
( C ) 17
( D ) 23
ANS-( B )
27. Kleinfelter’s syndrome is characterised by
( A ) XYY
( B ) XO
( C ) XXX
( D ) XXY
ANS-( D )
28. Grasshopper is an example of XO type of sex determination in which males have:
( A ) one X chromosome
( B ) no Y-chromosome
( C ) two X-chromosome
( D ) no X-chromosome
ANS-( A )
29. Father of a child is colourblind and mother is carrier for colourblindness,the possibility of the child being colourblind is:
( A ) 25 %
( B ) 50 %
( C ) 100 %
( D ) 75 %
ANS-( B )
30. Female’s with Turner’s syndrome have
( A ) small uterus
( B ) rudimentary ovaries
( C ) underdeveloped breasts
( D ) all of these
ANS-( D )
31. Trisohry is represented by
( A ) (2n – 1)
( B ) (2n – 2 )
( C ) (2n + 2)
( D ) (2n + 1)
ANS-( D )
32. A couple has six daughters. What is the possibility of their having a girl next time
( A ) 10 %
( B ) 50 %
( C ) 90 %
( D ) 100 %
ANS-( B )
33. What can be the blood group of offspring AB blood when group both? parents have
( A ) AB only
( B ) A, B & AB
( C ) A, B, AB & O
( D ) A & B only
ANS – ( B )
34. A normal vision female whose father is colour-blind marries a normal vision male What would be the probability of her sons and daughters to be colour blind?
( A ) 25 % sons colourblind and all daughters with phenotypically normal vision
( B ) 50 % sons colourblind and 50 % daughters normal.
( C ) 50 % sons colourblind and 50 % daughter colour blind.
( D ) Allsons normal and 50 % colourblind daughter
ANS-( B )
35. A family has 5 daughters. Probability of 6th child being boy will be:
( A ) 1 in 2
( B ) 1 in 5
( C ) 1 in 3
( D ) 1 in 6
ANS-( A )
36. A genotype AaBBCcDD can produce how many types of gametes?
( A ) 4
( B ) 3
( C ) 16
( D ) 64
ANS-( A )
37. In a dihybrid test cross the genotypic ratio of the progeny is:
( A ) 9: 3: 3: 1
( B ) 1: 1: 1: 1
( C ) 3: 1: 2: 1
( D ) 1: 7: 1
ANS-( B )
38. If mother has ‘ O ‘ blood group and child also has ‘ O ‘ group. What will be the blood group of Father?
( A ) O
( B ) A
( C ) B
( D ) AB
ANS-( A )
39. Child has blood group o ‘ and his father is’ B ‘ type. Then genotype of the father should be:
( A ) IBIB
( B ) IB IO
( C ) IA IB
( D ) lOIO
ANS-( B )
40. Antiserum used in testing blood groups has:
( A ) Antibody
( B ) Antigen
( C ) Leucocytes
( D ) None
ANS-( A )
