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Showing 1 question in Biology for Class 10. Tap a card to reveal the answer.
BiologyHeredity and EvolutionmediumIn a monohybrid cross between a tall pea plant (TT) and a short pea plant (tt), what is the ratio of tall to short plants in the F2 generation? Explain briefly.
Reveal answer ↓
What it is
Crossing two hybrids (Tt x Tt) gives a 3:1 tall-to-short ratio because T is dominant over t.
Answer
The F1 generation is all Tt (tall), because T is dominant over t. When F1 plants (Tt x Tt) are crossed, the F2 offspring are TT, Tt, Tt, tt. TT, Tt and Tt appear tall while tt is short, giving a phenotypic ratio of 3 tall : 1 short. The genotypic ratio is 1 TT : 2 Tt : 1 tt.
Tt x Tt -> 3 tall : 1 short (phenotype)
- •F1 all Tt (tall) - T dominant
- •F2 phenotypic ratio 3 tall : 1 short
- •F2 genotypic ratio 1:2:1
- •Illustrates Mendel's law of dominance and segregation
Why learn this
It's the foundation of genetics, inherited diseases and modern crop and gene science.
💡 Memory trick
Tt x Tt -> 3 tall : 1 short (phenotype), 1:2:1 (genotype). The classic Mendel 3:1.