Question

Give an account of incomplete dominance with a suitable example.

Answer 1

Incomplete dominance:

1. Incomplete dominance is a deviation from Mendel’s law of dominance.
2. In incomplete dominance, both the alleles (genes) of an allelomorphic pair express themselves partially.
3. One allele (gene) cannot suppress the expression of the other allele (gene) completely.
4. In such a case, there is an intermediate expression in the F1 hybrid.
5. In Mirabilis jalapa, if a red-flowered (RR) plant is crossed with a white-flowered (rr) plant, then F1 offspring have pink (Rr) flowers.

F2 Generation: Selfing of F1

Result:
Genotypic ratio - 1 RR : 2 Rr : 1rr
Phenotypic ratio - 1 Red: 2 Pink :1 White