A woman heterozygous for color blindness (an X-linked recessive allele) marries a man with normal color vision.What is the probability that their first child will be color blind?
A) 25%
B) 50%
C) 75%
D) 100%
E) none of these

Question

Quizplus · Accepted Answer

The woman is a carrier (X^CX^c) and the man has normal vision (X^CY). The possible offspring are X^CX^C, X^CX^c, X^CY, and X^cY. Only X^cY (a male) will be color blind, which is 25% of the total possibilities.

A Woman Heterozygous for Color Blindness (An X-Linked Recessive Allele)