In a dihybrid cross of AABB X aabb with AaBb F1 heterozygotes, what is the ratio of the F1 gametes (AB, aB, Ab, ab) that will give rise to the F2 offspring?
A) 1.1:1:1
B) 1:3:3:1
C) 1:2:2:1
D) 4.3:2:1

Correct Answer: (A) 1:1:1:1

Explanation:

The AaBb F1 heterozygotes are produced from the combination of parent AABB X aabb.

The AaBb parent produces four possible combinations of gametes.

Half of the gametes are with a dominant A and dominant B allele; the remaining half of the gametes possess recessive a and recessive b allele.

Thus, both parents produce an equal proportion of AB, Ab, aB, and ab. Thus, all these combinations are 25% each.

Therefore, AB:Ab:aB:ab = 1:1:1:1.

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Updated on: 20-Mar-2023

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