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Science (086) — AI-generated practice question

AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.

Q1. [1] straightforward exam-ready
In a monohybrid cross between tall (Tt) and short (tt) pea plants, what is the expected ratio of tall to short plants in the progeny?
  1. A 3:1
  2. B 1:1
  3. C 2:1
  4. D 1:2:1
Generated by claude-sonnet-4-6 · 2026-06-26 01:02 · grounding rag
Model Answer

Answer: B) 1:1

Cross: Tt × tt → Tt, Tt, tt, tt
Tall (Tt) : Short (tt) = 1:1

Source: Chapter 8, Section 8.2.2

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Explanation

This is a test cross (not F2 self-pollination). When Tt × tt, the gametes are T/t from the tall parent and only t from the short parent, giving 50% Tt (tall) and 50% tt (short) — ratio 1:1. Students often confuse this with the F2 ratio (3:1, from Tt × Tt) or the genotypic ratio (1:2:1). Remember: 3:1 and 1:2:1 come from crossing two heterozygotes (Tt × Tt), not from a cross with a homozygous recessive (tt).

Previous-year CBSE Grade 10 board exam questions, organised by subject and chapter, each with a model answer — free to read and print.