A male human is heterozygous for autosomal genes A and B and is also hemizygous for hemophilic gene h. What proportion of his sperms will be abh?
- 1/16
- 1/32
- 1/8
- 1/4
Answer
(3) 1/8
Solution
Genotype of the male: AaBb XhY (haemophilia gene h is on the X chromosome; the male has only one X, so he is hemizygous).
⇒ Probability of a sperm carrying a = 12
⇒ Probability of carrying b = 12
⇒ Probability of carrying Xh (h) = 12 (the other half carry Y)
∵ The genes segregate independently,
proportion of abh sperms = 12 12 12 = 18
Answer: (3)