Crossing true-breeding pea plants with yellow peas with true-breeding plants with green peas yielded an F1 generation with 100% offspring plants with yellow peas. The F1 plants are self-fertilized and produce F2. In a randomly selected set of 100 peas from F2 you notice the following phenotypic numbers: 64 yellow and 36 green. Using the Hardy-Weinberg principle: What is the observed frequency of the dominant allele in this F2 population?

From the observation in the F1 generation it can be concluded the Allele for yellow pea is dominate over that for green pea. Thus in the F2 generation, any pea showing yellow coloration is heterozygous having only one allele for yellow coloration and the green coloration will be homozygous.

For this calculation let's assume A as the allele for yellow coloration and "a" as the allele for green coloration.

The total population is 100.

Genetic frequency is , Aa = 64/100 = 0.64

aa = 36/100 = 0.36

The frequency of the dominant allele A = (0.5×0.64) = 0.32

The frequency of the dominant allele is reducing with each generation.

Thus applied the Hardy-weinberg principle, it can be concluded that external forces have impacted the allele equilibrium in this community as it is noticed that the frequency of the dominant allele has reduced.