Choose a trait and each parent’s genotype. Predict how many of four offspring show the dominant trait, then solve the Punnett square.
Each parent carries two alleles for a trait and passes one to each offspring. A Punnett square lays out every possible combination of the parents’ gametes.
A dominant allele (X) masks a recessive one (x). So XX and Xx both show the dominant trait; only xx shows the recessive trait.
Cross two heterozygous parents (Xx × Xx) and the phenotype ratio is 3 dominant : 1 recessive, with a 1:2:1 genotype ratio (XX : Xx : xx).
You’ve solved five crosses and predicted their phenotype ratios, the inheritance patterns of the eternal genome are yours to command.