In a dihybrid cross AA bb × aa BB, what proportion of the F₂ offspring is expected to be homozygous for at least one gene? A)1/4 B)1/2 C)3/4 D)All are homozygotes. E)None are homozygotes.

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In a dihybrid cross AA bb × aa BB, all F1 offspring will be heterozygous for both genes (AaBb). However, when considering the proportion of offspring that are homozygous for at least one gene in the next generation, we must consider all possible combinations. The possible genotypes for the genes in question are AA, Aa, or aa for the first gene, and BB, Bb, or bb for the second gene. The only way an offspring is not homozygous for at least one gene is if they are AaBb. The combinations that result in at least one homozygous gene are: AAbb, aaBB, AABb, aaBb, AaBB, and AAbb, which are 3/4 of all possible combinations.

In a Dihybrid Cross AA Bb × Aa BB, What