Question

Which of the following pairs is incorrect about the phenotypic ratio of $F_2$ generation about gene interactions?

• A. Dihybrid $F_2$ ratio — 9 : 3 : 3 : 1
• B. Monohybrid $F_1$ ratio — 1 : 1 : 1 : 1
• C. Incomplete dominance — 1 : 2 : 1
• D. Dominant epistasis — 12 : 3 : 1

Answer 1

The correct option is B Monohybrid $F_1$ ratio — 1 : 1 : 1 : 1

1 : 1 : 1 : 1 is the ratio of dihybrid test cross. In a monohybrid cross, we start with true-breeding parents (one homozygous dominant, one homozygous recessive), all of the $F_1$ progeny will be heterozygous and show the dominant phenotype, and then these will give rise to a 3 : 1 ratio of phenotypes in the $F_2$ generation.