Question

When red and white flowered Mirabilis plants are crossed all pink flowers are seen in F generation. When F progeny is selfed, the expected phenotypic and genotypic ratios are

• A. 1:2:1 and 3:1:1
• B. 3:1 and 1:2:1
• C. 1:2:1 and 1:2:1
• D. 1:1 and 1:1:1

Answer 1

Answer: (C)

1:2:1 and 1:2:1

Answer 2

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