In Drosophila, the red-eye allele for eye color exhibits complete dominance over the recessive white-eye allele. In some of Thomas Hunt Morgan's initial experiments, he crossed red-eyed female flies with white-eyed males. When he then crossed the F₁ red-eyed heterozygous females with red-eyed males, Morgan found that half of the male progeny were white-eyed. What is the MOST likely explanation of this result?

Question

Quizplus · Accepted Answer

The gene for eye color in Drosophila is located on the X chromosome. This explains why half of the male progeny (which inherit their X chromosome from their mother and their Y chromosome from their father) were white-eyed when the red-eyed heterozygous females were crossed with red-eyed males. Males only have one X chromosome, so if they inherit the X chromosome with the white-eye allele from their mother, they will express the white-eye phenotype.

In Drosophila, the Red-Eye Allele for Eye Color Exhibits Complete