Understanding the Genotypes
* XRXr: This female fruit fly is heterozygous for the eye color gene. She has one dominant "red eye" allele (XR) and one recessive "white eye" allele (Xr). Since the red eye allele is dominant, she will have red eyes.
* XRy: This male fruit fly is hemizygous for the eye color gene. He has one X chromosome with the dominant "red eye" allele (XR) and a Y chromosome (which doesn't carry the eye color gene). He will also have red eyes.
Setting Up the Punnett Square
Since eye color in fruit flies is a sex-linked trait, we need to consider the X chromosomes. Here's how the Punnett Square looks:
```
XR Y
XR XRXR XRY
Xr XRXr XrY
```
Interpreting the Results
* XRXR: Female, red eyes
* XRY: Male, red eyes
* XRXr: Female, red eyes
* XrY: Male, white eyes
Conclusion
The resulting offspring will have the following phenotypes:
* 75% Red-eyed Flies: This includes both females and males.
* 25% White-eyed Flies: These will be all male.
Key Point: The white-eyed trait is only expressed in males because they only have one X chromosome. If they inherit the recessive "white eye" allele, they lack a dominant "red eye" allele to mask it.
