What is the purpose of a test cross in genetics?

A test cross is primarily used to identify an individual's genotype, particularly when the specific genetic makeup is unclear. This method involves crossing the organism in question, which may have a dominant phenotype (observable trait), with an organism that is homozygous recessive for the trait of interest.

The results of the offspring will reveal whether the individual being tested is homozygous dominant (two identical dominant alleles) or heterozygous (one dominant allele and one recessive allele). If all offspring resemble the dominant phenotype, the tested individual is likely homozygous dominant. If there are offspring that display the recessive phenotype, this indicates that the tested individual is heterozygous.

Understanding the genotype of an organism is crucial in genetics. It aids in predicting the inheritance patterns of traits in subsequent generations and can be instrumental in breeding programs or genetic studies.