A tall pea plant (TT) is crossed with a short pea plant (tt). All F1 plants are tall, and when F1 plants self…

Question

A tall pea plant (TT) is crossed with a short pea plant (tt). All F1 plants are tall, and when F1 plants self-pollinate, tall and short plants appear in the F2 generation in a 3:1 ratio. Which of the following best explains these observations?
((A)) Tallness is dominant; the allele for shortness is masked in F1 but reappears in F2
((B)) Shortness is dominant; the allele for tallness disappears in F1
((C)) The tall allele blends with the short allele in F1 but separates again in F2
((D)) Only tall plants can self-pollinate successfully

Accepted Answer

## Model Answer **(B) Tall is a dominant trait** Tallness is dominant over shortness. In F1, all plants are Tt (tall), as T masks t. In F2, self-pollination gives TT : Tt : tt = 3 tall : 1 short, showing the recessive allele reappears. ## Explanation The examiner expects you to identify **dominance and recessiveness** as the explanation. The key NCERT concept is: "the trait that gets expressed is called the dominant trait and the other is called the recessive trait." Option A in the original choices matches this, but from the given OPTIONS list, **(B) Tall is a dominant trait** is the correct answer. Remember: the 3:1 ratio in F2 is the classic Mendelian result proving dominance, not blending.

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