What offspring would you expect from a cross between the female Drosophila described in problem 1 (red eyes and a yellow body, homozygous recessive for the yellow body color allele and homozygous dominant for the eye color allele) and the male described in problem 2 (hemizygous for both the recessive (white) eye color allele and dominant (tan) body color allele?) A reminder that the alleles for eye color and for body color are on the X chromosome of Drosophila, but not on the Y. Red eye color (w+) is dominant to white eye color (w), and tan body color (y+) is dominant to yellow body color (y).

Genotypes and phenotypes of parents

The yellow-bodied, red-eyed female is homozygous for the dominant red-eye color and for the recessive yellow-body color. The tan-bodied, white-eyed male is hemizygous for both the recessive white-eye color and the dominant tan-body color.

The daughters inherit a dominant red-eye allele from the mother and a dominant tan-body allele from the father. They are heterozygous for both eye and body color. Since the alleles for eye color and for body color are on the X chromosome of Drosophila, the sons inherit these traits from the mother only. Their phenotype is the same as that of the mother.