Question

In Drosophila, white eye color is a recessive X-linked trait while red eye color is dominant. A white-eyed female is crossed with a red-eyed male. The female offspring with red eye color would be

• A. 100%
• B. 50%
• C. 25%
• D. Zero

Answer 1

The correct option is A

100%

The white-eyed female (ww) produces gametes with only (w) allele. The male fly is red-eyed and produces gametes half of which carry (R) allele while the other half carry the Y chromosome. The progeny would comprise of 50% females and 50% males. All these females would be red-eyed (Rw; red being dominant), while the males would be white-eyed. The image below will explain the inheritance pattern.