The answer is the Law of segregation.
This asserts that the two alleles for a gene unconnected throughout gamete development, and end up in dissimilar gametes. In the case of the heterozygous green-pod plant (Gg), one gamete will obtain the dominant allele (G), and the other gamete will obtain the recessive allele (g). The law of segregation explains for the prediction that 50% of the offspring of the test cross will have green pods and 50% will have yellow pods.
