Question

A girl is color blind (XrXr; recessive, sex linked)

a. What are the possible genotypes and phenotypes of her parents?

b. Assuming that her mother is normal, what were this girl’s chances of being born with color blindness?

c. If she married a normal husband, what would be the possible genotypes and phenotypes of her offspring?

Answer 1

A.

Dad is definitely XrY(colorblind),

mom can be either XRXr(heterozygous,carrier, not colorblind) or XrXr(colorblind)

B. 50%(for XRXr*XrY)

C. So the cross’ll be XrXr*XRY. All the boys will be colorblind(XrY). The girls will be carriers of the recessive allele(XRXr).

Hope this helps:)