Final answer:
A genetic cross between two pea plants with genotype Gg results in a 3:1 ratio of green to yellow pods, using a Punnett Square to determine the expected phenotypes.
Step-by-step explanation:
If you do a genetic cross between two pea plants, both with the genotype Gg, the expected ratio of green (dominant) to yellow (recessive) pods can be determined using a Punnett Square. Each parent can pass on either a G (dominant green allele) or g (recessive yellow allele). When you set up the Punnett Square, the possible genotypes are GG, Gg, Gg, and gg. Since green is dominant, both GG and Gg genotypes result in green pods, while only the gg genotype results in yellow pods. This gives a phenotypic ratio of 3 green to 1 yellow.
In this cross, the offspring genotypes that result in green pods (GG and Gg) are three-quarters of the possibilities, while the genotype for yellow pods (gg) is one-quarter. Hence, the expected ratio of green to yellow pods is 3:1.