In cats, an X-linked locus is responsible for fur color. There are two known alleles at this locus. One results in black fur color; the other results in orange fur color. A heterozygote animal has patches of orange and black fur (tortoiseshell). Which coat color phenotypes are expected from the cross of a black female and an orange male?
A) tortoiseshell females; tortoiseshell males
B) black females; orange males
C) tortoiseshell females; black males
D) orange females; black males

Question

Quizplus · Accepted Answer

Since the fur color gene is X-linked, females have two X chromosomes and can be heterozygous, displaying the tortoiseshell phenotype. Males, having only one X chromosome, will express the allele present on their single X chromosome. A black female (X^bX^b) crossed with an orange male (X^oY) will produce tortoiseshell females (X^bX^o) and black males (X^bY), as males inherit their X chromosome from their mother and their Y chromosome from their father.

In Cats, an X-Linked Locus Is Responsible for Fur Color