In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes 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 female; black male

B) black female; orange male

C) tortoiseshell female; tortoiseshell male

A) tortoiseshell female; black male

Explanation:

Females have two X chromosomes and males have an X and a Y chromosome.

The possible genotypes and phenotypes are:

XᵒXᵒ: black female XᵒY: black male XᴼXᴼ: orange female XᴼY: orange male XᵒXᴼ: tortoiseshell female

Cross of a black female and an orange male

XᵒXᵒ x XᴼY

The female only produces Xᵒ gametes. The male produces Xᴼ and Y.

The possible offspring therefore is: XᵒXᴼ (tortoiseshell females) and XᵒY (black males). The answer is A.