Question

When red and white flowered Mirabilis plants are crossed all pink flowers are seen in F1 generation.

Answer 1

Sometimes two genes of the allelomorphic pair do not show a dominant-recessive relationship, but when presents together, they show intermediate trait or incomplete dominance. Incomplete dominance is not blending inheritance because parental characters reappear in F2 generation. ln Mirabilis jalapa, there are two types of pure breeding plants, red flowered and white flowered. On crossing them the F1 plants or hybrids possess pink flowers. On selfing them, F2 generation has plants in the ratio of 1 red: 2 pinks: 1 white-flowered plants with the phenotypic ratio being the same as a genotypic ratio.

Genotypic ratio= 1RR: 2Rr: 1rr

Phenotypic ratio: 1 Red : 2 Pink : 1 White

Both genotypic ratio and phenotypic ratio are same,

i.e., 1 :2 :1.