Question

Test cross in pea plant is:

• A. A cross between F2 tall plant and recessive parent.
• B. A cross between F2 dwarf plant and recessive parent.
• C. A cross between F2 tall plant with dominant parent.
• D. A cross between two F1 plants.

Hint:

Test crosses are fundamental tools in genetic analysis to infer the genetic composition of an organism.

Answer 1

The Correct Option is A

Test cross in pea plants is A cross between F1 tall plant and recessive parent.

(A) F1 tall × recessive parent - Correct: This reveals the F1 genotype (Tt) by crossing with homozygous recessive (tt).

(B) F1 dwarf × recessive parent - Incorrect: F1 generation shows only dominant phenotype in Mendel's experiments.

(C) F1 tall × dominant parent - Incorrect: Wouldn't distinguish homozygous vs heterozygous dominants.

(D) Two F1 plants - Incorrect: This produces F2 generation, not a test cross.

The correct answer is (A), as test crosses always use recessive parents to determine unknown genotypes.

Answer 2

A test cross is used to determine the genotype of an individual with a dominant phenotype. By crossing it with a recessive homozygous individual, we can observe the offspring to deduce whether the dominant parent is homozygous or heterozygous. In the case of pea plants, if a tall (dominant) plant is crossed with a recessive dwarf plant, the result will help us determine the genotype of the tall plant.

Option (A) is correct because it describes the correct test cross between a tall plant (F2 generation) and a recessive dwarf plant.