Solution:  The seeds of F1 plants are round and yellow. In the F2 generation, crossing between generations can result in new combinations of round-yellow, round green, wrinkled yellow, and wrinkled green in the ratio of 9: 3: 3: 1.

This shows that whether a pea seed is round or wrinkled is independent of whether it is yellow or green. As a result, each pair of alleles is unrelated to the other. This is referred to as an independent assortment.