How Do Mendel's Experiments Show That Traits Are Inherited Independently?

Mendel selected pea plants and focused on two completely separate traits at the exact same time:

• Trait 1 (Shape): Round seeds (Dominant - R) vs. Wrinkled seeds (Recessive - r).
• Trait 2 (Color): Yellow seeds (Dominant - Y) vs. Green seeds (Recessive - y). He crossed a pure plant having Round & Yellow seeds (RRYY) with a pure plant having Wrinkled & Green seeds (rryy).

When the seeds grew, all the plants in the first (F1) generation produced Round & Yellow seeds (RrYy).

• This was entirely expected because Round and Yellow are the 'Dominant' boss genes that hide the weaker green and wrinkled genes.

Mendel then took these F1 plants (RrYy) and allowed them to self-pollinate. This is where the magic happened. The plants produced four entirely different massive combinations of seeds:

1. Round & Yellow (Original parent combination)
2. Wrinkled & Green (Original parent combination)
3. Round & Green (Completely NEW combination!)
4. Wrinkled & Yellow (Completely NEW combination!)

The sudden appearance of the new, mixed combinations (Round with Green, and Wrinkled with Yellow) proved his theory perfectly.

• It proved that the gene for 'Seed Shape' is NOT permanently glued to the gene for 'Seed Color'.
• When the gametes (sperms and eggs) are formed, the traits split up and mix completely independently of each other. A seed can inherit the yellow color without being forced to inherit the round shape.