Question

What is a test cross? How can it decipher the heterozygosity of a plant?

Answer 1

Test cross involves the breeding of an individual with a phenotypically recessive individual. In order to determine the zygosity of the former, the proportions of the offspring phenotypes must be analyzed. Zygosity can be heterozygous or homozygous.

In the diagram, recessive (yy) is cross bred with the individual to know its zygosity. If all are yellow colored, then the individual is homozygous (YY) but if half are yellow and half are green, then the individual is heterozygous.