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NDA 2020 GAT · General Knowledge · Genetics and Heredity · medium

When a pure tall pea plant (TT) is crossed with a pure dwarf plant (tt) and the F1 plants are self-pollinated, the ratio of tall to dwarf plants in…

Single correct option

When a pure tall pea plant (TT) is crossed with a pure dwarf plant (tt) and the F1 plants are self-pollinated, the ratio of tall to dwarf plants in F2 is
  1. A. 3 : 1
  2. B. 1 : 1
  3. C. 1 : 3
  4. D. 9 : 3
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Answer: (A) 3 : 1

F1 plants are all Tt and tall. Selfing Tt x Tt gives TT, Tt, Tt and tt, so three plants are tall and one is dwarf, in the ratio 3 : 1. The genotype ratio is 1 : 2 : 1. The ratio 1 : 1 is the test cross result of Tt x tt.
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Original question written in the NDA 2020 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake