Punnett Square Punnett squares are used to determine the possible genetic combinations in the offspring from a cross between two parents Both parents have 2 alleles for each gene. During meiosis, the chromosomes that these alleles are on are separated - each gamete gets only one alleles for each gene.

Punnett Squares   As a result of fertilization, the parents’ alleles combine to give the offspring 2 alleles for a gene. This is what Mendel predicted in his Law of Segregation

Example: A heterozygous green pea plant (Gg) is crossed with a plant that is also a heterozygous green pea plant (Gg).