question_answer

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

A)                 must have normal colour vision

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

C)                 must be colourblind

D)                 may be colourblind or may be of normal vision

Correct Answer: D

Solution :

                Colourblindness is a sex linked (X-linked) trait. It always transfers from mother to son.                 A woman/whose father was colour blind, will be carrier for colour blind trait. Marriage of this woman with a colourblind man will result of the above possibilities.