Question

What shall be the ratio of heterozygous, homozygous and colour blind hemizygous in offspring of a colour blind husband and a carrier wife?

• A. 1:1:2
• B. 1:1:1
• C. 2:1:1
• D. 1:2:1

Answer 1

The correct option is B 1:1:1

Colour blindness is a X-linked recessive disorder. Genotype of carrier female will be (X${}^c$X) and that of colour blind man will be (X${}^c$Y). The ratio of heterozygous, homozygous and colourblind hemizygous in offspring will be 1:1:1. Correct answer is option B.

Parent generation : X${}^c$X x X${}^c$Y

Gametes : X${}^c$X --> X${}^c$Y	X${}^c$	X
X${}^c$	X${}^c$X${}^c$ homozygous colour blind girl	X${}^c$X heterozygous carrier girl
Y	X${}^c$Y hemizygous colour blind boy	XY normal boy