Question

the results of thomas hunt morgans last cross are shown in the punnett square below. which of thomas hunt morgans hypotheses was valid based on these results? white eyes are lethal in female drosophila. white eyes are lethal in male drosophila.

Explanation:

In the Punnett - square, we see female flies with genotype \(X^{R}X^{r}\) (red - eyed carriers) and male flies with genotype \(X^{r}Y\) (white - eyed). Since there are no female flies with the homozygous recessive white - eyed genotype (\(X^{r}X^{r}\)), it could imply that white eyes are lethal in female Drosophila. There are white - eyed male flies (\(X^{r}Y\)), so white eyes are not lethal in male Drosophila.

Answer:

White eyes are lethal in female Drosophila.