Mendel discovered that yellow seed color in pea plants is dominant to green. what offspring genotype probabilities are expected for a cross between a plant that produces yellow seeds (heterozygous genotype) and one that produces green seeds

Pea plants with yellow color, which are heterozygous have a genotype Aa

Pea plants with green color have a genotype aa (homozygous recessive).

If we cross them:

Parents: Aa x aa

F1 generation: Aa Aa aa aa

This means that half of the offspring will have yellow color (Aa genotype) and half of them will be green (aa genotype).