Question

When a pure-tall pea plant is crossed with a pure-dwarf pea plant, the percentage of tall pea plants in F₁ and F₂ generation pea plants will be, respectively, ______.

Options

• 100%; 25%

• 100%; 50%

• 100%; 75%

• 100%; 100%

Answer 1

When a pure-tall pea plant is crossed with a pure-dwarf pea plant, the percentage of tall pea plants in F₁ and F₂ generation pea plants will be, respectively, 100%; 75%.

Explanation:

When a pure-tall (TT) pea plant is crossed with a pure-dwarf (tt) pea plant, all of the heterozygous (Tt) offspring in the F₁ generation will be tall. Tall (TT, Tt) to dwarf (tt) plants will make up a 3 : 1 ratio of the F₂ generation when the F₁ generation (Tt) is self-pollinated. Therefore, the percentage of tall pea plants will be:

F₁ generation: 100% tall (since all plants are Tt.)

F₂ generation: 75% tall (from the ratio 3 : 1)