As mentioned in question E11, red eyes is the wild-type phenotype in Drosophila. Several different genes (with each gene existing in two or more alleles) are known to affect eye color. One allele causes purple eyes, and a different allele causes sepia eyes. Both of these alleles are recessive to the red eye color allele. When flies with purple eyes were crossed to flies with sepia eyes, all of the F1 offspring had red eyes. When the F1 offspring were allowed to mate with each other, the following results were obtained:

146 purple eyes 151 sepia eyes 50 purplish sepia eyes 444 red eyes Explain this pattern of inheritance. Conduct a chi square test to see if the experimental data fit your hypothesis.