Question

What is the cross between the progeny of F${}_1$ and the homozygous recessive parent called? How is it useful?

Answer 1

Test cross

The cross between the progeny of F${}_1$ and the homozygous recessive parent is called test cross.

For example, a cross between a homozygous tall (TT) plant with a homozygous dwarf (tt) plant produces heterozygous tall progenies (Tt) in the F${}_1$ generation.

In the test cross, heterozygous tall progeny (Tt) of the F${}_1$ generation is crossed with a plant genetically identical to its homozygous recessive parent (tt) as given below:



Use of test cross

Test cross is an important tool in genetics as it tells us about the genotype of an unknown pea plant (whether homozygous or heterozygous) showing dominant traits for certain characters.