Ans.The Punnett square is a diagram (in the form of a checker board) that is used to predict an outcome of a particular cross or breeding experiment. It is named after R. C. Punnett (an English mathematician). The gametes of both parents having all possible genetic set-ups are determined A checker board is used to cross all the possible gametes of one parent with all the gametes of other parent. In this way, a biologist can find all the possible genotypes of offsprings.