NEETZoologyPrinciples of Inheritance and Variation
In a certain monohybrid cross, the F₁ offspring exhibit a phenotype that does not resemble either of the two parents and is intermediate between them. Upon selfing of these F₁ individuals, the F₂ generation produces a phenotypic ratio that is exactly identical to its genotypic ratio (1:2:1). Which of the following examples best represents this genetic phenomenon?
Options
- AABO blood grouping in humans
- BSkin colour in humans
- CPhenylketonuria
- DFlower colour in dog flower
Correct answer
D. Flower colour in dog flower
Step-by-step solution
The phenomenon described is incomplete dominance, where the F₁ phenotype is intermediate between the two parents and does not resemble either of them completely. In incomplete dominance, the F₂ phenotypic ratio is 1:2:1, which is identical to the genotypic ratio. Flower colour in dog flower (Antirrhinum) is a classic example of incomplete dominance. ABO blood grouping is an example of co-dominance and multiple allelism. Skin colour in humans is an example of polygenic inheritance, which shows continuous variation.