The Living World 8th Edition by George Johnson

Exercise 17

Your instructor presents you with a Drosophila (fruit fly) with red eyes, as well as a stock of white-eyed flies and another stock of flies homozygous for the red-eye allele. You know that the presence of white eyes in Drosophila is caused by a recessive allele. How would you determine whether the single red-eyed fly was heterozygous for the white-eye allele?