In Mirabilis, a hybrid for red (RR) and white (rr) flower produces pink (Rr) flower. A plant with pink flower is crossed with white flower, the expected phenotypic ratio is

Question

Q. In Antirrhinum, two plants with pink flowers were hybridized. The F

_{1}

plants produced red, pink and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype of the two plants used for hybridization. Red flower colour is determined by RR, and white by rr genes?

Answer 1

The phenotype ratio represents the percentage of offspring within the given population that possess a particular physical characteristic. In the case of Mirabilis, the cross between homozygous parents (red and white) gives a F

_{1}

generation which is heterozygous (all pink- Rr). The crossing of the F

_{1}

generations will give rise to F

_{2}

generation. However, here it is a case of the backcrossing where a hybrid (Pink- Rr) is crossed with one parent (White- rr) flowers. The resultant phenotype will, therefore, be in the ratio 1:1 (Pink: White) as the cross is made with a recessive parent.

Answer 2

So, the correct answer is option B.