Some of the offspring of two gray bodied flies are black. what can you conclude about the genotypes of the parent flies?

The genotypes of the parent flies is heterozygous for the gray color.

Explanation:

A single gene coding for body color in flies is involved here. Based on the information provided in the question, one allele is gray (G) while the other is black (g).

According to the question, two gray bodied flies mates and gives rise to some black bodied offsprings. This can only occur because the allele for black color is present in the genotype of the parents. Hence, in other words, the parents genotypes consists of both gray and black color alleles. In this case, they are said to be heterozygous i.e. contain different alleles.

Based on Mendel's law of dominance, this further illustrates that since the black allele was present in both parents genotypes but phenotypically masked by the gray color allele, the dominant allele is the Gray allele (G) while the recessive allele is the black color allele (g). The black color can therefore, only be expressed in a homozygous state i.e. gg