question_answer

A woman with normal vision, but whose father was colorblind, marries a colorblind man. Suppose that the fourth child of this couple was a boy. This boy

A)  must have normal color vision

B)  will be partially colorblind since he is heterozygous for the colorblind mutant allele

C)  must be colorblind

D)  may be colorblind or may be of normal vision

Correct Answer: D

Solution :

Colorblindness is a sex linked (X-linked) trait It always transfers from mother to son. A woman, whose father was colorblind, will cross be carrier for colorblind trait. Marriage of this woman with a colorblind man will result of the following possibilities.