CBSE Class 10 Answered

In plants like 4-0-clock (Mirabilis jalapa) and snapdragon (Antirrhinum) ,if red flowered plants are crossed with white flowered ones, F1 produces all pink flowers. Dominance thus appears to be partial or incomplete. In F2, we get red, white and pink flowers.

      Gametes                         R                            ×                 r       

                                             │­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­________________________│

                                                                           │

    F₁                                                                   Rr(pink)

Selfing                              Rr                              ×                   Rr

In F2 generation, the phenotypic ratio of red:pink:white flowers = 1:2:1.

The genotypic ratio is RR:Rr:rr = 1:2:1. Thus it can be seen that phenotypic and genotypic ratios are same.