A cross of red-eye female (X^R X^R) x white-eye male (X^r Y) Drosophila produced 200 offspring. F1 was self-crossed and F2 phenotypes recorded.
Why are no white-eye females observed?
- A
White-eye allele is lethal in females.
- Bcheck_circle
F1 females are heterozygous (X^R X^r); none of the F2 females inherits two recessive alleles.
- C
Mutation rate differs between sexes.
- D
Males alone carry the white allele.
Explanation
F1 females are X^R X^r and F1 males are X^R Y. Among F2: X^R X^R, X^R X^r, X^R Y, X^r Y. No X^r X^r is produced from this F1, so no white-eye females appear.