Question

What would happen when two pink flowering snapdragon plants are crossed? Which among the following Punnett squares shows the right cross with the correct flower colours of the progeny.

• A.

  	R	r
  R	Red	Red
  r	Red	Pink

• B.

  	r	R
  r	pink	Red
  R	Red	Red

• C.

  	R	r
  R	Red	Pink
  r	Pink	Pink

• D.

  	R	r
  R	Red	Pink
  r	Pink	White

Answer 1

The correct option is D

	R	r
R	Red	Pink
r	Pink	White

In incomplete dominance or partial dominance, the heterozygous phenotype is intermediate between both homozygous parents; It is because of the haplo-insufficiency (only one copy of the wild allele is not sufficient for normal expression of the trait) of the wild allele. This is seen in the case of Antirrhinum (snapdragon), a cross between red coloured snapdragon flower and white coloured flower plants results in the production of a pink coloured flower plant in the $F_1$ generation, and neither of the parental phenotypes get masked. And when this $F_1$ progeny are crossed with one another, the progeny of the $F_2$ generation comes in a ratio of 1(red): 2(pink): 1(white). The aboven given cross is the $F_2$ generation of snapdragon monohybrid cross.