Question

In fruit flies, eye color is a sex-linked trait. Red is dominant to white.

What are the sexes and eye colors of flies with the following genotypes:

(4 points)
Male with red eyes Female with Red eyes Male with white eyes Female with white eyes




















XRY
XrY
XrXr
XRXr

Answer 1

In fruit flies, eye color is determined by sex-linked genes, with the red eye color (R) being dominant over the white eye color (r). The alleles are located on the X chromosome, and males have one X and one Y chromosome (XY), while females have two X chromosomes (XX).

Let's analyze each genotype you provided:

1. **Male with red eyes: XRY**
- Sex: Male (XY)
- Eye color: Red (dominant trait)

2. **Female with red eyes: XRXr**
- Sex: Female (XX)
- Eye color: Red (has one dominant red allele)

3. **Male with white eyes: XrY**
- Sex: Male (XY)
- Eye color: White (homozygous recessive)

4. **Female with white eyes: XrXr**
- Sex: Female (XX)
- Eye color: White (homozygous recessive)

So the summaries are:

- Male with red eyes: Male, Red
- Female with red eyes: Female, Red
- Male with white eyes: Male, White
- Female with white eyes: Female, White