Question

How is F2 progeny obtained by self-pollination of F1 progeny different from F1 progeny? Give reason for this observation.

Answer 1

Mendel's observation:

1. The experiment that Mendel conducted involved two steps.
2. In the first step, he crossed two plants of garden pea out of which one plant was short and the other tall.
3. The off-springs produced after this cross was only tall plants. This generation was called the F1 generation or first filial generation.
4. In the second step, he crossed two plants of the F1 generation.
5. As a result, he got both tall and dwarf plants which he called F2 generation or second filial generation plants.
6. In the F2 generation, one-third of the plants were short and the rest plants were tall.
7. This was expressed as TT (homogenous tall), tt (homogenous short), and Tt (heterogenous tall) in the ratio of 1:2:1 (TT:Tt: tt).

Reason for this observation:

1. Mendel observed different results because of the nature of genes to dominate.
2. The gene, for the tall character was dominant in this case and thus it masked the effect of the gene for the short character.
3. In the F2 generation, both of these characters got expressed.

Figure showing cross for tall and dwarf characters: