Solutions For An Introduction to Genetic Analysis Chapter 3 Problem 38P

A cross is made in the species of moths. Both the male and female are dark. When these two organisms are crossed, all the male progeny are dark. The half of the female progeny is light and the rest half are dark.

Since the results of the cross are specific to the sex of the moths, sex-linked inheritance can be considered. In moths, females are heterogametic while the males are homogametic.

Assuming D for dark as the dominant allele and d for light, then the data can be explained as dark male being heterozygous (D/d) and the dark female being hemizygous (D).

Parents:

Progeny:

The males will inherit the D allele from their mother and be dark. Half the females will inherit D from their father and be dark, while the other half will inherit d from the father and be light.