Question

If you cross a red eyed pure breeding female Drosophila with a white eyed male, then the F1 males so produces were crossed with white eyed male, what will be the eye colour of their daughters and sons in F2?

(a) Both daughters and sons red eyed

(b) Daughters with both eye colour while sons with white eye

(c) Both daughters and sons with both eye colours

(d) Daughters with red eye and sons with white eyes

I have been asked this question in an interview.

Enquiry is from Chromosomal Theory of Inheritance in section Chromosomal Basis of Inheritance of Cytogenetics

Answer 1

The correct choice is (d) Daughters with red eye and sons with white eyes

To elaborate: Eye colour is a sex linked trait. In this following case, the F1 male progeny was red eyed, as the father only gave the Y chromosome and not X which determines eye colour. Then similarly the F2 sons would be white eyed by allele from their mother, female will be red eyed as they get both allels.