Explain incomplete dominance with suitable example
Solution
Incomplete dominance:
a. Incomplete dominance can be defined as a phenomenon in which neither of the alleles of a gene is completely dominant over the other and hybrid is intermediate between the two parents.
b. Incomplete dominance is a deviation of Mendel’s law of dominance which states that out of two contrasting allelomorphic factors, only one expresses itself in an individual in F1 generation called as dominant, while other which has not shown its effect is called
as recessive, however this recessive hidden character reappeared, unchanged in F2 generation.
c. Thus, according to incomplete dominance, F1 phenotype is intermediate between the parental traits. Incomplete dominance is demonstrated in Mirabilis jalapa (four o’clock
plant) as given below:
This indicates the following facts:
a. Pink is the phenotype of the heterozygous genotype (Rr).
b. This pattern of inheritance is due to non-blending of the characters, because one-fourth of the F2 progeny are red-flowered and another one-fourth are white-flowered, which are the parental combinations.
c. The phenotypic and genotypic ratios are the same.
d. This type of observation has resulted from incomplete dominance of the alleles
