Question

The phenotypic and genotypic ratio in incomplete dominance is
A. 1:2:1
B. 9:3:3:1
C. 3:1 D. 9:7

Answer 1

Incomplete dominance is a type of inheritance and in it gives rise to offsprings with intermediates traits. In other words, in this type, one allele is not completely dominant over another and the offsprings inherit a mix of both dominant and recessive parental traits resulting in a new phenotype.

Complete answer: In incomplete dominance a single gene pair is involved and neither of them is dominant with respect to each other.
There is a deviation from the ratio obtained in the Mendelian monohybrid cross.
In the F2 generation, gives rise to similar results both in terms of phenotypic ratio and genotypic ratio which is 1:2:1.
This can be seen in the plant snapdragon, where the cross between red and white flowered snapdragon plants results in an offspring having pink-colored flowers.

This can be well understood by the following cross:

So, the correct answer is option A. 1:2:1.

Note: As there is the blending of both alleles, and none of them get expressed alone, so this type of inheritance is known as partial dominance or semi-dominance.
Another example of this type of inheritance can be observed in the tail length of dogs.