Back Cross

A back cross is a cross between an F1 hybrid and either one of its two parental genotypes, and it comes in two forms - a dominant back cross (F1 crossed back to the dominant parent) and a recessive back cross (F1 crossed back to the recessive parent). Crossing the F1 hybrid to the dominant parent produces offspring that are entirely dominant in phenotype, with no recessive individuals appearing at all. Crossing the F1 hybrid to the recessive parent, by contrast, produces both phenotypes in equal (1:1) proportion - and this particular kind of back cross is exactly what is called a test cross, because it is this specific cross (F1 x recessive parent) that reveals whether the F1 individual is heterozygous. In other words, every test …