Q.Explain independent assortment with a suitable example.

Step 1. Statement. The Law of Independent Assortment states that when a hybrid possessing two (or more) pairs of contrasting factors forms gametes, the factors of each pair segregate independently of the other pair(s).

Step 2. Example set-up. Cross a pure round-yellow (RRYY) pea plant with a pure wrinkled-green (rryy) plant. The F1 is RrYy (Round, Yellow).

Step 3. Independent gamete formation. If the two gene pairs assorted together, the RrYy F1 would produce only the two parental gamete types, RY and ry. Instead, because the genes lie on separate chromosome pairs, they assort independently, and the F1 produces all four possible gamete types — RY, Ry, rY, ry — in equal proportion, including the two new (recombinant) combinations Ry and rY that neither parent had.

Step 4. F2 confirmation. Selfing F1 x F1 and combining these four gamete types across a 4×4 Punnett square gives an F2 phenotypic ratio of 9 Round-Yellow : 3 Round-Green : 3 Wrinkled-Yellow : 1 Wrinkled-Green — the presence of the new Round-Green and Wrinkled-Yellow classes (in a 3:3 ratio) is only possible because the two traits assorted independently rather than staying bound to their original parental pairing.

Contrast the four independently-assorted gamete types against the two parental-only gamete types that linkage would instead predict.

• Failing to point out that independent assortment specifically requires the genes to lie on different chromosomes (linked genes on the same chromosome do not assort independently, as Morgan later showed).