Mendel crossed a pure tall pea plant (TT) with a pure short pea plant (tt) and obtained all tall plants in F1 generation.
Generated by claude-sonnet-4-6 · 2026-06-15 06:52 · grounding rag
Model Answer
(a) The gene combination in F1 plants is Tt (hybrid tall).
(b) 'T' (tallness) is a dominant trait. A single copy of 'T' is enough to make the plant tall, so 'tt' (shortness) being recessive is not expressed in F1.
(c) The ratio of plants in F2 generation is 3 tall : 1 short (i.e., 1 TT : 2 Tt : 1 tt).
Source: Chapter 8, Section 8.2.2
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Explanation
- Examiners expect the genotype Tt for part (a) — not just "hybrid."
- For part (b), use the key terms dominant and recessive; state that one copy of T is sufficient.
- For part (c), the phenotypic ratio 3:1 is essential. Writing the genotypic ratio 1:2:1 alongside shows deeper understanding but the phenotypic ratio is the primary answer expected here.
- All three parts together carry 2 marks, so keep each answer to one line.