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Science — CBSE Class 10 board question

Q1. [1]
When a pure-tall pea plant is crossed with a pure-dwarf pea plant, the percentage of tall pea plants in F₁ and F₂ generation pea plants will be respectively :
  1. (a) 100% ; 25%
  2. (b) 100% ; 50%
  3. (c) 100% ; 75%
  4. (d) 100% ; 100%
Previously asked in CBSE board exam
2025 31/4/1 Q9
Generated by claude-sonnet-4-6 · 2026-06-15 06:53 · grounding rag
Model Answer

(c) 100% ; 75%

When pure-tall (TT) is crossed with pure-dwarf (tt), all F₁ plants are Tt (tall) = 100% tall. In F₂, ratio is 1TT : 2Tt : 1tt, giving 3 tall : 1 dwarf = 75% tall.

Explanation

Remember: tall is dominant over dwarf. F₁ gives 100% tall (all Tt). In F₂, self-crossing Tt × Tt gives the classic 3:1 Mendelian ratio — 75% tall, 25% dwarf. This is the foundational result of Mendel's monohybrid cross.

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