Question

White eyes in male fruit fly is determined by a ______.

Options

• dominant gene on X

• recessive gene on Y

• dominant gene on Y

• recessive gene on X

Answer 1

White eyes in male fruit fly is determined by a recessive gene on X.

Explanation:

White eyes in male fruit flies (Drosophila melanogaster) are due to a recessive gene located on the X chromosome. Males have only one X chromosome, so if they inherit the recessive allele for white eyes on their single X chromosome, they will express the white eye trait. There is no corresponding gene on the Y chromosome. This sex-linked inheritance pattern was demonstrated by Thomas Hunt Morgan in his experiments with fruit flies, showing that the white eye mutation is recessive and X-linked.