Question

What is a test cross ? Show phenotypic ratio 1:1 in a monohybrid test cross through punnet square.

Answer 1

	R	r
r	Rr	rr
r	Rr	rr

The cross between heterozygous F${}_1$ hybrid and the double recessive homozygous is known as the test cross.

Trait: Seed shape

Alleles: R- Round, r- Wrinkled

Cross: Wrinkled seeds × Round seeds

(rr) (Rr)

Genotypic ratio: 1:1

Phenotypic ratio: 1:1