Question

What is test cross? Give example?

Answer 1

A test cross involves crossing of an individual of dominant phenotype whose genotype is unknown with an organism showing homozygous recessive genotype/phenotype. Using this cross we can know the genotype of the dominant phenotypic parent. For example, if Tall trait is dominant over Dwarf trait, we take a tall plant whose genotype is not known and cross it with a dwarf plant whose genotype obviously is homozygous recessive. If the dominant parent was homozygous, we would not get any recessive offspring but if the dominant parent was heterozygous, we will get 50% of offspring as recessive ones.