Explain with an example how traits get expressed?

The gene which decides the appearance of an organism even in the presence of an alternative gene is known as a dominant gene. The trait expressed is known as a dominant trait. The dominant gene is represented by a capital letter. The gene which decides the appearance of an organism only in the presence of another identical gene is called a recessive gene. The trait expressed is known as a recessive trait. The recessive gene is represented by a small letter. For example, Pure tall (TT) pea plant was crossed with dwarf (tt) plant.

$F_1$ Generation: All plants obtained were heterozygous tall (Tt). Plants from $F_1$ generation were self-pollinated to obtain $F_2$ generation.

$F_2$ Generation: One homozygous tall plant (TT), two heterozygous tall plants (Tt) and one homozygous dwarf plant (tt) were obtained.