The alleles for the purple color of the flowers of pea plant are dominant over the alleles for the white color of the flowers. The purple color can be expressed in the following to genotypes: PP and Pp, where P is the dominant purple color gene and p is the recessive white color gene. When two parents both heterozygous for purple color are crossed with each other, they give the following genotypes in the progeny: PP, 2 x Pp and pp. The following Punnett square represents the genotypes.