In the dihybrid cross Aa Bb × aa bb, what proportion of heterozygotes for both gene pairs is expected among the F₁ offspring? A)1/4 B)1/2 C)3/4 D)All are heterozygotes. E)None are heterozygotes.

Question

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In the cross Aa Bb × aa bb, the possible gametes from Aa Bb are AB, Ab, aB, and ab, while from aa bb, the only possible gamete is ab. The heterozygote for both genes (Aa Bb) can only be formed from the combination of Ab from Aa Bb and ab from aa bb, which occurs in 1 out of 4 possible combinations, giving a proportion of 1/4.

In the Dihybrid Cross Aa Bb × Aa Bb, What