Question

Pure-tall (TT) pea plants are crossed with pure-dwarf (tt) pea plants. The pea plants obtained in F₁ generation are then self pollinated to produce F₂ generation.

1. What do the plants of F₁ generation look-like? Justify your answer.
2. What is the ratio of pure-tall plants to pure-dwarf plants in F₂ generation?

Answer 1

i. When pure dwarf (tt) pea plants are crossed with pure tall (TT) pea plants, the genotype Tt will be present in all F₁ generation plants. All F₁ plants will be tall, as T (tall) is dominant over t (dwarf).

	T	T
t	Tt	Tt
t	Tt	Tt

Here is a 100% tall plant where ‘T’ is a dominant character (Tallness).

ii. The F₂ generation is a cross between two members of the F₁ generation.

	T	t
T	TT	Tt	F2 generation
t	Tt	tt

As a result, the ratio of pure tall to pure dwarf is 25%, or 1 : 1.