Cinnabar eye color is an X-linked, recessive characteristic in fruit flies. If a female having cinnabar eyes is crossed with a male having wild-type, red eyes, what percent of the F1 males will have cinnabar eyes?

Question

Quizplus · Accepted Answer

Since cinnabar eye color is X-linked and recessive, and the female parent has cinnabar eyes, she must have two copies of the recessive allele (being XX). The male, having wild-type eyes, has a normal allele on his X chromosome. All male offspring (XY) will inherit their X chromosome from their mother and their Y chromosome from their father. Therefore, all male offspring will inherit the cinnabar allele from their mother and exhibit cinnabar eyes.

Cinnabar Eye Color Is an X-Linked, Recessive Characteristic in Fruit