Multiple choice

A genetic experiment was performed to map the gene (s) for eye colour in a newly-discovered moth species. Sex determination in this moth species: XY — male and XX — female. When blue-eyed males were mated to green-eyed females, all of both male and female progeny had green eyes. When these progeny were mated among themselves, about half of the males of the resulting second generation had blue eyes; however, all females were green-eyed. Which one of the following is consistent with the above data?

  1. Multiple genes control eye colour in this moth species.

  2. Gene(s) for eye colour is located on the X chromosome.

  3. Gene(s) for eye colour is located on the Y chromosome.

  4. Gene(s) for eye colour may not be sex-linked.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In this species, males are XY and females are XX. When blue-eyed males are crossed with green-eyed females, all F1 progeny are green, indicating green is dominant. In the F2 generation, half of the males have blue eyes while all females are green-eyed, which is the classic sex-linked recessive inheritance pattern corresponding to genes on the X chromosome.

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