In an F2 generation only male fruit flies had white eyes What is this pattern of inheritance called?

Answer 1

Any trait that segregates strictly by sex would be a SEX-LINKED trait. So I suppose you could call this "sex-linked inheritance". In this case, it appears that there is a mutation in the "white" gene (which normally makes the pigment that turns the eyes red, by the way) on the X chromosome. Since only the males are displaying the phenotype, it would probably mean that the mother was heterozygous w/+ for this gene (+ indicates wild-type, which in this case translates to "red-eyed"). Furthermore, I can infer that the fathers were red-eyed +/Y (since if they were white-eyed, you would see some white-eyed female progeny), and that not all of the male progeny were white eyed (since half of them should have inherited the + copy of the gene). So your males should be approximately half w/Y and half +/Y, and the females should be half w/+ and half +/+. This type of inheritance called criss cross inheritance fom father to grandson through daughter.