In a monohybrid cross, when you cross two heterozygous individuals (for example, Aa x Aa), the genotypic ratio in the F2 generation typically follows Mendel's laws of inheritance. The genotype frequencies for a monohybrid cross of two heterozygous parents result in the following ratios:
- Homozygous dominant (AA): 1
- Heterozygous (Aa): 2
- Homozygous recessive (aa): 1
This can be summarized as a ratio of 1:2:1 for the genotypes.
To find the frequency of the heterozygous genotype (Aa) among the total offspring, you take the number of heterozygous individuals over the total number of individuals:
- Total = 1 (AA) + 2 (Aa) + 1 (aa) = 4
- Frequency of heterozygous Aa = 2/4 = 1/2 or 50%.
So, the frequency of a heterozygous genotype (Aa) in the F2 generation from a monohybrid cross of two heterozygous parents is 50%.