In genetics, what does a Punnett square illustrate?

A Punnett square is a graphical representation used in genetics to predict the possible genotypes of offspring resulting from a particular genetic cross between two parents. By illustrating the possible allele combinations that can occur when gametes fuse during fertilization, the Punnett square allows geneticists to calculate the probabilities of inheriting specific traits.

Each cell in the square represents a possible genotype of the offspring, derived from one allele contributed by each parent. By organizing the alleles in this way, it clearly shows the relationship between parent genotypes and the potential outcomes for their children. This tool is particularly useful in studies involving Mendelian inheritance, where dominant and recessive traits can be analyzed.

In contrast, the other options focus on aspects that are not represented by a Punnett square. The physical traits of parents are not directly shown; mutation rates pertain to population genetics rather than individual crosses; and while inheritance patterns are related concepts, a Punnett square specifically illustrates the potential genotypes rather than the broader patterns throughout generations.