The key difference between test cross and backcross is that the test cross is the cross that occurs between a dominant phenotype and a recessive phenotype while the backcross is the cross that occurs between generation F1 hybrid and one of the two parents.
Understanding the difference between test cross and backcross is important in genetics as they are two different types of crosses that are extremely helpful to identify the genotype of an animal or a plant. The major objective of performing the test cross and backcross is to discover the heterozygosity or homozygosity of individuals by identifying the types of gametes that produce the dominant genotypes.
Consider the following example to understand both crosses and the difference between test cross and backcross. Here, ‘T’ denotes the dominant trait of the tall pea plant, and ‘t’ denotes the recessive trait of the same phenotype. A tall pea plant hybrid can either exist as homozygous (TT) or heterozygous (Tt) and the dwarf plant hybrid is always homozygous recessive (tt).
