In cats, black fur color is determined by an X-linked allele; the other allele at this locus determines orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect 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

The black female is homozygous for the black allele on her X chromosome, while the orange male is hemizygous for the orange allele on his X chromosome. Their offspring will inherit one X chromosome from each parent, resulting in females that are heterozygous for the black and orange allele and therefore tortoiseshell. Male offspring will inherit the black allele from the female and the Y chromosome from the male and will be black. Therefore, the only possible outcome is tortoiseshell females and black males.

In Cats, Black Fur Color Is Determined by an X-Linked