The genotype of this fly is w+/w+/XY.
How to determine genotype?
To determine the genotypes of the flies, consider the inheritance patterns of eye color in Drosophila melanogaster (fruit flies).
Eye color: There are two main alleles for eye color in fruit flies - white (w) and red (w+). Red is dominant over white, meaning a fly with one w+ allele and one w allele will have red eyes (heterozygous). A fly with two w alleles will have white eyes (homozygous recessive).
Sex: Fruit flies have XX sex chromosomes for females and XY for males.
a. white eyed, male:
White eyes indicate two w alleles (ww).
Males have XY chromosomes.
Therefore, the genotype of this fly is wW/XY.
b. red eyed female (heterozygous):
Red eyes indicate at least one w+ allele.
Heterozygous means one w+ allele and one w allele.
Females have XX chromosomes.
Therefore, the genotype of this fly is w+/w/XX.
c. white eyed, female:
White eyes indicate two w alleles (ww).
Females have XX chromosomes.
Therefore, the genotype of this fly is ww/XX.
d. red eyed, male:
Red eyes indicate at least one w+ allele.
Males have XY chromosomes.
Since only the w+ allele can result in red eyes in males, this fly must have two w+ alleles (homozygous dominant).
Therefore, the genotype of this fly is w+/w+/XY.