nt gene for green peas will have the AA genotype, and a plant homozygous for the recessive gene for yellow peas will have the aa genotype. Heterozygous plants will have the genotype Aa and will have green peas. In a monohybrid cross, the parents will have the phenotypes AA and aa. In the F1 generation (offspring), all the plants will be heterozygotes with the Aa genotype and have green peas. In the second generation, which combines two heterozygotes with each other, there is one chance in four of a homozygous dominant offspring (AA), one chance in four of a homozygous recessive offspring (aa), and one chance in two of a heterozygous offspring (Aa). Since the dominant gene, A, codes for green peas, three quarters of the offspring will produce green peas, and one quarter will produce yellow peas. This is Mendelian genetics.
In a dihybrid cross, two traits are followed at once, such as color and shape (141
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