A recessive allele on the X chromosome causes color deficiency. A noncolor- deficient woman (whose father is color deficient) marries a color- deficient man. If they have a son, what is the chance that he will be color deficient?

Question

Quizplus · Accepted Answer

The mother is a carrier of the color deficiency allele (XcX) because her father was color deficient. The father is color deficient (XcY). The son will inherit one X chromosome from the mother and one Y chromosome from the father. There is a 50% chance he will inherit the Xc from the mother, making him color deficient.

A Recessive Allele on the X Chromosome Causes Color Deficiency