Question

A male human is heterozygous for autosomal genes A and B and is also hemizygous for the haemophilic gene h. What proportion of his sperms would be abX${}^h$?

• A. 1/8
• B. 1/32
• C. 1/16
• D. 1/4

Answer 1

The correct option is A 1/8

Autosomal genes are the ones which are present on the autosomes. According to the question, a male individual is heterozygous for autosomal genes A and B. He is also hemizygous for the haemophilic gene ‘h’. His genotype therefore would be AaBbX${}^h$Y.
During meiosis, due to segregation of these alleles into the gametes, each gamete would receive only one of the 2 alleles. So, if we consider the alleles that would be carried by the sperms, it would carry either A or a, B or b and X${}^h$ or Y. The probability of sperms to be of the genotype abX${}^h$, would be a product of the individual probabilities of each gene.
The probability of a (out of a and A)= ½
The probability of b (out of b and B)=½
The probability of X${}^h$ (out of X${}^h$ and Y)= ½
Hence the probability of a sperm carrying abXh genotype would be= ½ X ½ X ½ = ⅛