When a white-eyed female fruit fly is crossed with a red-eyed male, what are the expected phenotypes of the offspring?

To understand the expected phenotypes of the offspring from crossing a white-eyed female fruit fly with a red-eyed male, it is important to consider the genetics behind eye color in Drosophila melanogaster. The gene for eye color is located on the X chromosome, making it an example of a sex-linked trait.

In this scenario, we have:

• The white-eyed female, which is likely homozygous for the white eye allele (let's designate it as "X^w X^w").

• The red-eyed male, who carries the dominant red eye allele (designated "X^R Y").

When these two flies are crossed, the possible combinations of alleles in their offspring can be determined through a Punnett square. The female can contribute X^w (white eye) alleles, and the male can contribute either X^R (red eye) alleles or the Y chromosome.

The results from this cross yield the following combinations for the offspring:

1. X^R X^w (female with red eyes)

2. X^w Y (male with white eyes)

Thus, the offspring will consist of all females with red eyes and all males with white eyes. This supports the correct choice, wherein all females