Question

which of thomas hunt morgan’s hypotheses was valid based on these results? white eyes are lethal in female drosophila. white eyes are lethal in male drosophila. female drosophila with white eyes are homozygous recessive. white eyes are the dominant trait in female drosophila.

Explanation:

1. Analyze the first option: The Punnett square shows female genotypes \(X^R X^r\) (no white - eyed females with \(X^r X^r\) are present). If white eyes were lethal in females, it would explain the absence of \(X^r X^r\) (homozygous white - eyed females), as they would not survive.
2. Analyze the second option: The Punnett square has male genotypes \(X^r Y\) (white - eyed males), so white eyes are not lethal in males.
3. Analyze the third option: If white - eyed females were homozygous recessive (\(X^r X^r\)), we should see them in the Punnett square, but we don't. So this hypothesis is invalid.
4. Analyze the fourth option: The female genotypes are \(X^R X^r\) (red - eyed, since \(R\) is dominant over \(r\)), so white eyes are recessive, not dominant in females.

Answer:

A. White eyes are lethal in female Drosophila.