Question

$F _{2}$ generation in a Mendelian cross showed that both genotypic and phenotypic ratios are same as $1: 2: 1.$ It represents a case of

• A. Co-dominance
• B. Dihybrid cross
• C. Monohybrid cross with complete dominance
• D. Monohybrid cross with incomplete dominance

Answer 1

Answer: (D)

Monohybrid cross with incomplete dominance

Answer 2

The inheritance of flower colour in the dog flower (snapdragon or Antirrhinum sp.) is a good example which shows incomplete dominance. In a cross between true-breeding red-flowered (RR) and true- breeding white-flowered plants (rr), the F1 (Rr) was pink. When the F1 was self-pollinated the F1 resulted in the following ratio, 1 (RR) Red : 2 (Rr) Pink : 1 (rr) White. Here the genotype ratios were 1 : 2 : 1 as in any Mendelian monohybrid cross, but the phenotype ratios had changed from the 3 : 1 dominant: recessive ratio to 1:2: 1.