How do Mendel’s experiments show that traits may be dominant or recessive?

Explanation

Mendel selected true breeding tall (TT) and dwarf (tt) pea plants. Then, he crossed these two plants. The seeds formed after fertilization were grown and these plants that were formed represent the first filial or `F_(1)` generation. All the `F_(1)` plants obtained were tall.

Then, Mendel self-pollinated the F plants and observed that all plants obtained in the `F_(1)` generation were not tall. Instead, one-fourth of the `F_(2)` plants were short.

From this experiment, Mendel concluded that the `F_(1)` tall plants were not true breeding. They were carrying traits of both short height and tall height. They appeared tall only because the tall trait is dominant over the dwarf trait.