4. In the fruit fly, the allele for normal wings (W) is dominant over the allele for vestigial wings (w). A cross of two normal-winged flies produced 76 normal-winged and 23 vestigial-winged offspring. What are the genotypes of the two parent flies?

A. WW and ww
B. WW and Ww
C. Ww and ww
D. Ww and Ww
E. WW and WW

5. A man who has hemophilia and a woman who does not have hemophilia have a daughter who has hemophilia. Hemophilia is a recessive condition, and the gene is located on the X chromosome. What can be concluded?

A. The mother is a carrier for hemophilia
B. Hemophilia is not a sex-linked trait
C. Crossing-over has occurred
D. All subsequent daughters of this couple will have hemophilia
E. All sons of this couple will have hemophilia

To determine the genotypes of the two parent flies, we need to consider the inheritance pattern of the wing trait in fruit flies. According to the problem, the allele for normal wings is dominant (W) and the allele for vestigial wings is recessive (w). If two normal-winged flies produced offspring, some of which have vestigial wings, this indicates that both parent flies must carry the recessive allele. Therefore, both parent flies must be heterozygous (Ww) for the vestigial wing trait. This would result in the following possible offspring genotypes:

WW: normal-winged
Ww: normal-winged
Ww: normal-winged
ww: vestigial-winged

The offspring would therefore be in the ratio of 3:1, which matches the observed phenotypes. This supports the conclusion that the genotypes of the two parent flies were (D) Ww and Ww.

Hemophilia is a recessive condition located on the X chromosome, meaning it is a sex-linked trait. Since the father has hemophilia, he has the genotype X^hY. The mother does not have hemophilia, so she must have at least one normal allele, giving her the genotype X^HX either as homozygous normal (X^HX^H) or as a carrier (X^HX^h). For their daughter to have hemophilia, she must have inherited two X chromosomes with the hemophilia allele (X^hX^h), which means her mother must have been a carrier of hemophilia to pass on the X^h allele. Therefore, we can conclude that (A) The mother is a carrier for hemophilia.