Normal fruit flies have red eyes.Flies with mutations that block the function of the X-linked white gene have white eyes.The wild-type allele is completely dominant to mutant alleles.A cross between a white-eyed female fruit fly and a red-eyed male would generate which of the following types of progeny?
A)red-eyed females and white-eyed males
B)white-eyed females and red-eyed males
C)all red-eyed females and a 50:50 mixture of white-eyed and red-eyed males
D)all red-eyed males and a 50:50 mixture of white-eyed and red-eyed females
E)The result cannot be predicted because it depends on whether the female is homozygous or heterozygous.

Question

Quizplus · Accepted Answer

The white gene is X-linked, and since females have two X chromosomes, a white-eyed female must have two mutant alleles (ww). A red-eyed male, having only one X chromosome, must have the wild-type allele (W). Their offspring would include red-eyed females (Ww) and white-eyed males (wY), as females inherit one X chromosome from each parent and males inherit the Y chromosome from their father and the X chromosome from their mother.

Normal Fruit Flies Have Red Eyes