Understanding Punnett Squares: Predicting Genotypes and Phenotypes in the F2 Generation

A cross between a homozygous recessive individual and homozygous dominant individual in the parent generation produces which of the following genotypes in the F2 generation?

AA, Aa, and aa

If we cross a homozygous recessive individual with a homozygous dominant individual in the parent generation, the genotype of the F1 generation will be heterozygous (one dominant and one recessive allele). The F1 generation will have the genotype of Rr, where R represents the dominant allele and r represents the recessive allele.

When we cross the F1 generation with each other, we can use a Punnett square to determine the possible genotypes of the F2 generation. Each F1 individual will contribute one allele to the F2 generation. Therefore, the possible genotypes in the F2 generation will be:

– RR (homozygous dominant, 25% probability)
– Rr (heterozygous, 50% probability)
– rr (homozygous recessive, 25% probability)

The ratio of the genotypes in the F2 generation will be 1:2:1 (1 RR : 2 Rr : 1 rr). Similarly, the ratio of the phenotypes will be 3:1 (3 dominant: 1 recessive) as the dominant allele is expressed in heterozygous individuals.

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