Question

In Drosophila, normal wing shape is dominant to dumpy wings, and gray body is dominant to yellow. A fly homozygous for both dominant traits was crossed with a fly homozygous for both recessive traits. The F1 progeny were testcrossed. In the F2 generation there were 80 normal wing, gray body; 81 dumpy wing, yellow body; 19 normal wing, yellow body; 21 dumpy wing, gray body. These data indicate that the genes are: