Hi Raksha!! Hope you are doing well!! Test cross is a type of test conducted by specialized scientists to find out that an organism exhibiting a dominant trait is heterozygous or homozygous for a specific allele. The organism for which we have to check is crossed with an homozygous organism of the recessive  traits and the offspring of test cross is analysed.

Hello,

Test Cross in Genetics involves the breeding of an individual with a phenotypically recessive individual, in order to determine the zygosity of the former by analyzing proportions of offspring phenotypes. Zygosity can either be heterozygous or homozygous. Test crosses are used to test an individual's genotype by crossing it with an individual of a known genotype.