Question

The genotype ratio of incomplete dominance is:

• A. 3:1
• B. 1:2:1
• C. 1:1:2
• D. 9:3:3:1

Hint:

Incomplete dominance illustrates the blending of traits in heterozygous individuals.

Answer 1

The Correct Option is B

The genotype ratio in incomplete dominance is 1:2:1.

(A) 3:1 - Incorrect: This is phenotypic ratio in complete dominance.

(B) 1:2:1 - Correct: Shows 1 homozygous dominant : 2 heterozygous : 1 homozygous recessive (e.g., snapdragon flower color).

(C) 1:1:2 - Incorrect: Not a standard Mendelian ratio.

(D) 9:3:3:1 - Incorrect: This is dihybrid cross ratio.

The correct answer is (B) 1:2:1, where heterozygotes show intermediate phenotype.

Answer 2

Incomplete dominance occurs when the heterozygous genotype exhibits a phenotype that is intermediate between the two homozygous phenotypes. For example, in snapdragons, crossing a red-flowered (RR) plant with a white-flowered (WW) plant produces offspring with pink flowers (RW).

The genotypic ratio of incomplete dominance is typically 1:2:1, where:

• 1 represents the homozygous dominant (e.g., RR),
• 2 represents the heterozygous (e.g., RW),
• 1 represents the homozygous recessive (e.g., WW).

Option (B) is correct because the ratio in incomplete dominance is 1:2:1.