Q1. [1] § 8.2.2 Rules for the Inheritance of Traits – Mendel's Contributions
A cross between two tall pea plants resulted in offsprings having a few dwarf plants. The gene-combination of the parental plants must be
- A Tt and Tt
- B Tt and tt
- C TT and tt
- D TT and Tt
Previously asked in CBSE board exam
2024 31/3/1 Q12
Generated by claude-sonnet-4-6 · 2026-06-15 06:54 · grounding rag
Model Answer
Option A: Tt and Tt
When two tall plants with genotype Tt are crossed, offspring are TT : Tt : tt in ratio 1:2:1, producing 25% dwarf (tt) plants along with tall plants.
Explanation
Key logic: dwarf plants appear in offspring only if both parents carry the recessive allele 't'. A Tt × Tt cross gives ¼ tt (dwarf). Option B (Tt × tt) gives 50% dwarf — too many. Options C and D cannot produce dwarf offspring at all (TT is present). Examiners expect you to recall the Tt × Tt cross from Mendel's F1 self-pollination experiment.
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