Which mating combination would best help determine the genotype of a red-eyed, dark-bodied female Drosophila?

• A. Mating with a red-eyed, dark-bodied male
• B. Mating with a red-eyed, yellow-bodied male
• C. Mating with a white-eyed, dark-bodied male
• D. Mating with a white-eyed, yellow-bodied male

Answer: (D)

Determining the genotype of the red-eyed, dark-bodied female Drosophila is best accomplished by using a mating strategy that reveals the potential recessive alleles associated with the traits of interest. In this case, the goal is to ascertain whether the red-eyed, dark-bodied female has two dominant alleles (homozygous) or one dominant and one recessive allele (heterozygous) for each trait.

Mating the female with a white-eyed, yellow-bodied male serves this purpose effectively. Since the male expresses recessive traits (white eyes and yellow body), the offspring produced can provide insights into the female's genotype based on the phenotypes observed.

If any offspring exhibit the traits typical of the recessive alleles (white eyes or yellow body), it would indicate that the female carries a recessive allele for at least one of the traits in question. This allows for a clear determination of whether the red-eyed, dark-bodied female is homozygous or heterozygous for these traits.

In contrast, mating with a male that shares any dominant traits (like red eyes and dark body) would not be informative, as the offspring would not display the recessive characteristics necessary to deduce the female's genotype. Thus,