Question

In a Drosophila melanogaster _________________________, a fly with a dominant phenotype and unknown genotype is mated to one that has a recessive phenotype

Answer 1

A test cross in fruit fly genetics is used to determine the genetic makeup of an individual expressing dominant traits when crossed with a recessive partner, as demonstrated by the cross between wild-type and mutant-bodied Drosophila.

Step-by-step explanation:

In Drosophila melanogaster genetics, a test cross is an essential tool for determining the genotype of an individual with a dominant phenotype but an unknown genotype. When this individual is mated with one that has a recessive phenotype, the progeny's phenotypes can reveal whether the unknown genotype was heterozygous or homozygous for the dominant trait. In the situation described, where a true-breeding (homozygous) wild-type male fly is crossed with a true-breeding female with black body and cinnabar eyes, resulting in all F1 offspring displaying the wild-type phenotype, it suggests that both the gray body and red eye traits are dominant over their mutant alleles.