Question

What is test cross? Why is it so named?

Answer 1

Hint:The concept of test cross was introduced by Gregor Mendel. Gregor Mendel is also known as the father of genetics because of his remarkable work on pea plants which led to the discovery of fundamental laws of inheritance.

Complete answer:
The breeding of a dominant phenotype with the recessive phenotype is referred to as a test cross. Zygosity the dominant phenotype can be identified by the test cross. Zygosity is the degree of similarity between two alleles which determine the particular trait.

The zygosity is identified by the proportion of phenotypes occurring in the offspring. It can be either homozygous or heterozygous. Homozygous individual consists of either two dominant alleles or recessive alleles. Heterozygous individuals contain both dominant and recessive alleles of the genes.

If an individual exhibits the dominant phenotype the genotype of the particular individual would be either homozygous dominant or heterozygous. In this situation the exact genotype can be determined by performing a test Cross with an individual exhibiting this is the phenotype for that trait.

The genotypes of the recessive phenotype has always been homozygous recessive for that particular trait therefore the proportion of the phenotype in the offspring Mein describe the diversity of the dominant phenotype which is examined during the test cross.

By crossing to a homozygous recessive individual, the genotype of an unknown individual will be revealed in the offspring.
Test cross helps to determine the genotype of the individual. It has wide application in plant breeding experiments.

Note:Please do not get confused between the two terms - back cross and test cross as they mean completely different.
i) Test cross is done in order to determine the zygosity of the former and is done by crossing of dominant phenotype with homozygous recessive phenotype
ii) Backcross is done by crossing the hybrid organism with one of its parents or genetically identical individual to the parent.