Gregor Mendel crossbred two different pea plants. One of the plants had yellow peas (a dominant trait) and one of the plants had green peas (a recessive trait). The yellow pea plant was heterozygous for its trait meaning its alleles will be Yy. The green plant, because it is recessive, was homozygous for its trait, yy. When these plants were crossbred, two of the offspring resulted in heterozygous for the yellow trait and the other two offspring were homozygous for the green trait.