The phenotypic ratio of F2 generation in a Mendelian monohybrid cross is (a) 2:1 (b) 3:1 (c) 9:3:3:1 (d) 1:2:1

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Q. The phenotypic ratio of F2 generation in a Mendelian monohybrid cross is

(a) 2:1

(b) 3:1

(d) 1:2:1

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In a monohybrid cross with complete dominance, self-pollinating the F1 (heterozygous, Aa) gives an F2 phenotypic ratio of 3 dominant : 1 recessive.

Consider Mendel's classic monohybrid cross, e.g., tall (TT) × dwarf (tt) pea plants:

P generation: TT (tall) × tt (dwarf)
F1 generation: all Tt (tall) — since tallness is dominant, all F1 plants show the dominant phenotype though they are heterozygous.
F2 generation: self-pollinating F1 (Tt × Tt) gives a genotypic ratio of 1 TT : 2 Tt : 1 tt, but since T is completely dominant over t, both TT and Tt plants are phenotypically tall.
This gives a phenotypic ratio of 3 tall : 1 dwarf, i.e., 3:1. …

Q.The phenotypic ratio of F2 generation in a Mendelian monohybrid cross is