Question

Starting with a cross between AA and aa, the proportion of heterozygotes in the F2 progeny will be?

1) 1/8
2) 1/4
3) 1/3
4) 1/2
5) All heterozygotes

Answer 1

The proportion of heterozygotes in the F2 progeny from a cross between AA and aa is 1/2.

Step-by-step explanation:

The proportion of heterozygotes in the F2 progeny can be determined by using the Punnett square method. In this case, a cross between AA and aa is performed. The F2 progeny will have a heterozygous genotype if they inherit one dominant allele (A) and one recessive allele (a).

When crossing AA and aa, all offspring in the F1 generation will be heterozygous (Aa). Then, when the F1 generation is crossed with each other, the following genotypes and their respective ratios are expected in the F2 progeny: 1/4 AA, 1/2 Aa, and 1/4 aa. Therefore, the proportion of heterozygotes in the F2 progeny is 1/2 (option 4).