Question

A test cross is carried out to determine which of the following?

• A. Predict whether two traits are linked
• B. Determine the genotype of $F_2$ plant
• C. Assess the number of alleles of a gene
• D. Determine whether two species or varieties will breed successfully

Answer 1

The correct option is B Determine the genotype of $F_2$ plant

Introduction to test cross
A test cross is a cross between a dominant trait expressing plant (whose genotype needs to be identified) and another plant which is homozygous recessive for the same trait (genetically identical to its recessive parent).

Genotype determination of $F_2$ plant
Test cross is used to determine the genotype of the $F_2$ plant which expresses a dominant trait.
If all the progeny of test cross express the dominant trait only, the test plant is homozygous for the dominant allele.
If the dominant and recessive plant progeny produced are in the ratio of $1:1$, the test plant is heterozygous for the dominant allele.

Final answer
(c) Determine the genotype of $F_2$ plant