Genetics MCQs Part V

1) In 1956, an XXXY type abnormality was seen in three patients. This has a
a) female genotype
b) gynandromorph
c) male phenotype
d) female phenotype

2) Which one of the following is responsible for mental abnormalities in humans?
a) XXX and XY
b) XX and XXX
c) XO and XXX
d) XX and XO

3) Who has first described `Criminal syndrome`?
a) Levan
b) Sandberg
c) Turner
d) Lejeune

4) the Barr body in mammals represents
a) all the heterochromatin in female cells
b) one of the two X chromosomes in the somatic cells of females
c) all the heterochromatin in male and female cells
d) the Y-chromosome in the somatic cells of male

5) One Barr body is found in a man of genotype
a) XY
c) XX
d) XXY

6) Barr body is found in
a) male somatic cells
b) female somatic cells
c) sperms
d) ova

7) Foetal sex can be determined by examining cells from amniotic fluid looking for
a) Kinetochore
b) Chiasmata
c) Chromosomes
d) Barr bodies

8) If each somatic cell of a human male contains a single Barr body in its nucleus, the most likely genetic constitution of the person is
a) XO
b) XXY
c) XYY

9) Number of Barr bodies and Y-spots in XXXXXYY karyotype is
a) 5 and 2
b) 5 and 1
c) 4 and 2
d) 4 and 1

10) A barr body is a
a) supernumerary Y-chromosome
b) coiled inert X-chromosome
c) extranuclear molecule of DNA
d) connection between two X chromosomes

11) The sex of an unborn mammal can be predicted by
a) placental biopsy
b) examination of the chorion
c) amniocentesis
d) examining the mother`s blood

12) The technique which makes use of amniotic fluid for the detection of prenatal disorders is called
a) Endoscopy
b) Laproscopy
c) Natal endoscopy
d) Amniocentesis

13) Amniocentesis is a
a) process to determine any disease in the heart
b) process to determine any hereditary disease in the embryo
c) process to detect the diseases of brain
d) all of these

14) A pregnant woman who has an amniocentesis test done finds an extra Barr body in her embryo. The syndrome which is likely to be associated with the embryo is
a) Patau`s syndrome
b) Klinefelter`s syndrome

c) Down`s syndrome

d) Edward`s syndrome

15) Amniocentesis is a technique used for
a) estimating amino acid content in the amnion
b) measuring the size of the foetus
c) determining the sex of the foetus
d) determining the position of the foetus

16) Who studied sex-linked inheritance for the first time?
a) Pasteur
b) Morgan
c) Mendel
d) Khorana

17) Traits whose gene are located on the X chromosomes are known as
a) sex-limited
b) sex-influenced
c) sex-linked
d) sex-controlled

18) Normally, sex-linked genes are located in X-chromosomes in human beings. This indicates that
a) the X-chromosome is dominant over Y-chromosome
b) the X-chromosome is longer than the Y-chromosome
c) the Y-chromosome is longer than X-chromosome
d) the entire set of genes in the X-chromosome is different from that in the Y-chromosome

19) Women rarely experience sex-linked defects because they must be
a) homozygous
b) carriers
c) heterozygous
d) develop immunity

20) A single recessive trait which can express its effect should occur on
a) the X-chromosome of the male
b) the X-chromosome of the female
c) Any chromosome
d) Any autosome

21) A child gets sex-linked traits from the
a) father
b) mother
c) both father and mother
d) none of the above

22) Which character is sex-linked in Drosophila?
a) Red eye colour
b) White eye colour
c) Grey body colour
d) All of these

23) Red-green colour blindness appears due to
a) excessive drinking
b) inheritance
c) vitamin A deficiency
d) overactivity of adrenals

24) Colour blindness in man is a
a) sex-linked character
b) sex-linked character
c) sex-limited character
d) dominant character

25) In colour blindness, patients fail to distinguish
a) red colour
b) green colour
c) red from green colour
d) none

26) In which of the following situations could a woman also be colour blind?
a) If her father was normal and mother is a carrier
b) If her father was colour blind and mother normal (nor carrier)
c) If her father was colour blind and mother a carrier
d) If her father was normal and mother colour blind

27) If a colour blind woman marries a normal man their children will be
a) normal daughters
b) colour blind sons and daughters
c) colour blind sons and carrier daughters
d) colour blind sons and normal daughters

28) Colour blindness is caused by a single
a) dominant gene in the man
b) dominant gene in the woman
c) recessive gene in the woman
d) recessive gene in the man

29) Colour blindness is related with a defect in the
a) rods
b) cones
c) both of these
d) none of these

30) The disease with sex-linked inheritance is
a) Night blindness
b) Anaemia
c) Colour blindness
d) Cretinism

31) Colour blindness is found more in males than in females because
a) the males having a single affected X-chromosome are colour blind
b) heterozygous females are colour blind
c) males having affected Y-chromosomes are colour blind
d) affected X-chromosomes has a much higher affinity to Y-chromosome

32) If a colour blind man marries the daughter of a colour blind man, who herself has normal vision. Then in their progeny
a) all sons will be colour blind
b) all daughters will be colour blind
c) some daughters and all sons will be colour blind
d) 50% of the progeny will be colour blind

33) A girl of normal vision whose father was colour blind marries a man of normal vision whose father was also colour blind. Their sons would be (of total number of sons)
a) all colour blind
b) 50% colour blind
c) all normal
d) 25% colour blind

34) Colour blindness results from
a) inverted retina
b) abnormal cones
c) absence of rods
d) absence of eyelids

35) Ram is colour blind. What is the chance that his son will inherit colour blindness from him?
a) 0%
b) 25%
c) 50%
d) 100%

36) A colour blind man has a normal brother and a colour blind sister. With respect to the phenotypes of the parents, it is likely that
a) the father was colour blind and mother had normal vision
b) father had normal vision and mother was colour blind
c) both the father and the mother had normal vision
d) both the father and the mother were colour blind

37) A colour blind father may have a normal daughter but again a colour blind grandson through her. This indicates that the gene responsible for colour blindness is located on the
a) X-chromosome and is recessive
b) Y-chromosome and is dominant
c) Y-chromosomes and is recessive
d) X-chromosomes and is dominant

38) Carriers of colour blindness are
a) women
b) men
c) both
d) none of these

39) If the husband and wife have normal vision, but the fathers of both were colour blind, the probability of their first daughter being colour blind is
a) 100%
b) 50%
c) 25%
d) 0%

40) A colour blind man marries a daughter of normal woman and colour blind man. The ratio of carrier daughters, colour blind daughters, normal sons, and colour blind sons born to this couple will be
a) 1:0:1:0
b) 2:1:1:2
c) 1:1:1:1
d) 1:2:2:1

41) A colour blind girl is rare because she will be born only when
a) Parents have normal vision but grandparents were colour blind
b) Her mother is colour blind and father has normal vision
c) Her mother and maternal grandfather were colour blind
d) Her father and maternal grandfather were colour blind

42) A colour blind man has a colour blind sister but a normal brother. The phenotypes of the parents are
a) Both parents are normal
b) Both parents are colour blind
c) Normal father and colour blind mother
d) Mother carrier and father colour blind

43) Haemophilia is a disease caused by the deficiency of
a) RBCs
b) WBCs
c) Thromboplastin
d) Water in plasma

44) Haemophilia is
a) haemolysis
b) phagocytosis by WBCs
c) clumping of RBCs
d) a failure of blood clotting

45) Which of the following is sex-linked?
a) Polio
b) Haemophilia
c) Colour blindness
d) Both B and C

46) Haemophilia is a genetic disorder which causes
a) Loss of haemoglobin
b) Rheumatism
c) Blindness
d) Non-clotting of blood

47) The female children of a haemophiliac man and carrier woman are likely to be
a) all haemophiliac
b) all carriers
c) half normal and half carriers
d) half haemophiliac and half carriers

48) If a haemophiliac man marries a normal woman, the offspring will be
a) all normal
b) all haemophilic
c) boys haemophilic
d) girls haemophilic

49) A haemophiliac man marries a normal homozygous woman. What is the probability that their son will be haemophiliac?
a) 0%
b) 50%
c) 75%
d) 100%

50) A haemophiliac man marries a carrier woman. The percentage of daughters becoming haemophiliac shall be
a) 0%
b) 50%
c) 75%
d) 100%

51) Haemophilia is more common in males because it is a
a) recessive trait carried by the Y-chromosome
b) dominant trait carried by the Y-chromosome
c) recessive trait carried by the X-chromosome
d) dominant trait carried by the X-chromosome

52) Of a normal couple, half the sons are haemophiliac while half the daughters are carriers. The gene is located on the
a) Y-chromosome of father
b) single X-chromosome of father
c) X-chromosome of the mother
d) Both the X-chromosomes

53) Haemophilia most likely originated as a result of
a) the crossing over of two sex chromosomes
b) the separation of two homologous chromosomes
c) a nondisjunction of chromosome number 21
d) a gene mutation in the X-chromosome

54) It is well known that Queen Victoria of England was a carrier of the gene for haemophilia. Since this is an X-linked disease, it can be predicted that
a) all of her sons would have had disease
b) her father must definitely have had haemophilia
c) all of her daughters would have been carriers
d) haemophilia would have occurred in more of her male than her female descendants

55) Haemophilia is a genetic disorder in which
a) the blood count falls
b) blood clots form in the blood vessels
c) there is delayed coagulation of blood
d) none of the above

56) Which one is genetically similar to haemophila?
a) albinism
b) colour blindness
c) night blindness
d) none of these

57) A haemophiliac father and a homozygous normal mother will produce children who are
a) all normal
b) all haemophiliac
c) all normal but females will be carriers
d) some normal and some haemophiliac

58) A man is haemophilic. It indicates that he
a) has little amount of blood
b) is carrying a blood parasite
c) has inherited this condition from his father
d) has inherited this condition from his mother

59) Baldness is
a) sex-determined
b) sex-linked
c) sex-controlled
d) none of the above

60) A woman with straight hair mates with a man with curly hair and who is known to be heterozygous for the trait. What is the chance that their first child will have curly hair?
a) no chance
b) one in four
c) one in two
d) it is certain

61) Traits that are coded in autosomes but expressed in only one of the sexes are known as
a) sex-linked
b) sex-influenced
c) sex-limited
d) sex-controlled

62) Genes which are confined to the differential region of the Y-chromosome only are called
a) holandric
b) mutant
c) completely sex-linked
d) autosomal

63) If both parents of a male child are normal, what are the chances of the child being colour blind?
a) It is impossible

b) It is possible only if the mother`s father was colour blind

c) It is possible only if the father`s mother was colour blind
d) It is possible even when all the four grandparents had normal vision

64) Sita`s father has haemophilia, an X-linked recessive trait, but her husband
does not. What is the chance that her son will have the disease?

a) 0%
b) 25%
c) 50%
d) 100%

65) A man who carries a holandric gene in his Y-chromosome marries a normal woman. The said gene will be transmitted to
a) 50% of their sons
b) 50% of their daughters
c) all their daughters
d) All their sons

66) Joseph has hairy ears (hypertrichosis), a trait carried by a gene in his Y-chromosome. What is the chance that his grandson will inherit the trait from him?
a) 0%
b) 25%
c) 50%
d) 100%

67) The inheritance of ABO blood groups illustrates
a) Multiple allelism
b) Polypoidy
c) Incomplete dominance
d) None

68) ABO blood groups were discovered by
a) Darwin
b) Landsteiner
c) Huxley
d) Harvey

69) A person of blood group A can accept blood safely from
a) A and AB
b) AB and O
c) O and A
d) A only

70) The blood group with antigen A and antibody B is
a) A
b) AB
c) B
d) O

71) The blood group “B” is determined by gene alleles which are
d) None of these

72) Parents of blood groups “O” and “AB” cannot have a child
of group AB because


73) A person having blood group “O” can receive blood of
a) groups O, A, B and AB
b) groups A, B and AB
c) groups B and AB
d) group O only

74) In which blood group are antibodies absent?
a) A
b) AB
c) B
d) O

75) An injured person of unknown blood group needing immediate blood transfusion can be given the following blood group :
a) A
b) O
c) B
d) AB

76) Children of parents with blood groups “O” and “AB” will

a) O,A
b) A,B
c) A,AB
d) A,B,O

77) The child of “O” group has “B” group father. The genotype
of the father will be


78) A man of “A” blood group marries a woman of “AB” blood
group. Which group of progeny would indicate that the man is heterozygous?

a) O
b) A
c) B
d) AB

79) A child with a mother of “A” group and a father of “AB”
group will not have the following blood group:

a) A
b) AB
c) B
d) O

80) Which of the following blood groups belongs to the category of universal recipient?
a) A
b) AB
c) B
d) O

81) In human beings, multiple allelism controls the inheritance of
a) sickle-cell anaemia
b) colour blindness
c) phenylketonuria
d) blood groups

82) Agglutinogens are not found in blood groups
a) B
b) A
c) AB
d) O

83) People of AB blood group have
a) antigens A and B and their antibodies
b) antibodies A and B, but no antigens
c) antigens A and B, but no antibodies
d) antigen B and antibody A

84) If one parent belongs to blood group A and the other to B, their children
can possibly inherit

a) AB group only
b) A and B groups only
c) O and AB groups only
d) All the four groups

85) Which of the following is the universal blood donor?
a) Group “O”
b) Group “AB”
c) Group “A”
d) Group “B”

86) If RBCs of a person have antigens A and B, his serum will have
a) antiA
b) antiB
c) both
d) none

87) Apart from its importance in blood transfusion, the study of blood groups is also useful in
a) Personality
b) Settling paternity disputes
c) Both
d) None

88) In case of a mismatched blood transfusion
a) RBCs of the recipient agglutinate
b) RBCs of donated blood agglutinate
c) WBCs of donated blood agglutinate
d) WBCs of recipient agglutinate

89) What will happen if blood of group “B” is transfused into the
body of a person of group “A”?

a) The recipient remains normal
b) The recipient dies due to clumping of his own RBCs
c) The recipient dies due to clumping of the RBCs of the transfused blood
d) none of these

90) A man with blood group “B” marries a woman with blood group “A”
and their first child is having blood group B. what is the genotype of the


91) The Rh factor was discovered by
a) Huxley
b) Landsteiner
c) Weiner
d) Landsteiner and Weiner

92) Rh factor derives its name on the basis of
a) Chimpanzee
b) Man
c) Rhesus monkey
d) Rat

93) In the developing foetus, erythroblastosis foetalis is caused by
a) clumping of RBCs
b) failure of blood clotting
c) phagocytosis by WBCs
d) haemolysis

94) The second pregnancy of a woman terminates due to anaemia of the foetus. She has never had a blood transfusion. On the basis of this, which of the following is correct?
a) The child from the first pregnancy is Rh positive
b) The husband of the woman is Rh positive
c) The woman is Rh negative
d) All the above

95) Rh factor may be responsible for
a) Turner`s syndrome
c) Sickle-cell anaemia
d) Erythroblastosis foetalis

96) Which of the following could result in haemolysis in the foetus?
a) Rh incompatibility
b) AB incompatibility
c) AO incompatibility
d) BO incompatibility

97) The child suffers from erythroblastosis foetalis if

98) Biologically marriage between which of the following is prohibited due to the risk of erythroblastosis foetalis in some of their offspring ?

99) Monozygotic twins are formed when:
a) The first cleavage of the zygote separates the cells
b) no cleavage is performed in the zygote
c) two ova are fertilized at the same time
d) incomplete cleavage of zygotes takes place

100) Nature of identical twins is
a) polyzygotic
b) dizygotic
c) monozygotic
d) amphizygotic



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