Color blindness is a sex-linked trait.Which of the following parental genotypes could produce a color-blind female? (X' indicates the color-blind trait.)
A) X'X x XY
B) XX x X'Y
C) X'X x X'Y
D) X'X' x XY

Question

Quizplus · Accepted Answer

In order for a female to be color-blind, she must inherit the color-blind trait from both of her parents. Since color blindness is a sex-linked trait, a female can only inherit the trait from a father who is color-blind (since the mother's normal X chromosome will mask the color-blindness gene). The only parental genotype that includes a color-blind father is X'X x X'Y, where the father contributes his X' chromosome to the daughter. The other options either have a normal father or a mother who is color-blind (which is rare since the gene is located on the X chromosome).

Color Blindness Is a Sex-Linked Trait