Suppose that in Drosophila melanogaster an XXY female with white eyes (due to th

Question

Suppose that in Drosophila melanogaster an XXY female with white eyes (due to the w^1 allele on both copies of an attached X chromosome) is mated with a male that has a yellow body (due to the y allele on the X chromosome). Which of the following best describes the phenotypes and their proportions in the first-generation progeny?

a. All males will have white eyes and all females will have yellow bodies.

b. All males will have yellow bodies and all females will have white eyes.

c. All males will have white eyes and all females will be wild type.

d. All males will have yellow bodies and all females will be wild type.

e. All males and females will be wild type, although both yellow-bodied and white-eyed flies will appear in the F2 generation.

Explanation / Answer

XXY female genotype: XwXw XY male genotype: XyY It's hard to know what the wild types are since white eyes could be wild type (homozygous dominant) or homozygous recessive. Same with the body since there is no other genotype to compare with. But from the answer choices it seems that the wild types are something other than yellow and white, so those traits are likely recessive. Punnett Square: Xw Xw Xy XwXy XwXy Y XwY XwY All females are XwXy and males are XwY. So if the white eyed & yellow bodied traits are recessive (ie non-wild type), the females are wild type and the males will have white eyes. This is "C".

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.