Each box of a Punnett square represents the:

1. The combinations of egg and sperm are made in the boxes of the table to show which alleles are combining. 2. Each box then represents the diploid genotype of a zygote, or fertilized egg, that could result from this mating. 3. Because each possibility is equally likely, genotypic ratios can be read straight off the square. 4. The gametes are written along the edges of the square rather than inside the boxes. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 12 'Mendel's Experiments and Heredity', sections 12.1-12.3_