What is a Punnett square used for?

A Punnett square is a graphical representation used in genetics to predict the probability of the offspring inheriting specific genetic traits from their parents. It organizes all possible gametes (sperm and egg) from each parent, allowing one to visualize how alleles combine during fertilization. By filling in the square with these combinations, one can readily see the likelihood of different genotypes and phenotypes appearing in the offspring.

This tool is particularly useful for monohybrid and dihybrid crosses, as it systematically displays all possible outcomes based on the alleles involved. The percentages derived from the completed Punnett square reflect the potential genetic makeup of the next generation, making it an invaluable method in genetic studies.

The other choices do not align with the primary function of a Punnett square. For example, determining the chromosome number pertains to karyotyping rather than genetic probabilities, while analyzing gene expression involves understanding how genes are turned on and off, which is outside the scope of what a Punnett square provides. Identifying mutations in DNA requires molecular techniques rather than predictions about inheritance, which a Punnett square indicates.