What is a Punnett square used for?

• A. To visualize the distribution of traits in a population.
• B. To predict the possible genotypes and phenotypes of offspring from a given cross.
• C. To determine genetic linkage.
• D. To predict the exact future mutations.

Answer: (B)

Punnett squares are a tool to predict the possible genotypes and phenotypes of offspring from a cross by combining the alleles each parent can pass. By lining up one parent's possible gametes across the top and the other parent's across the side, you fill in the grid to see all potential allele combinations in the offspring. From those combinations, you can infer which traits are likely to appear and how often each outcome might occur, based on dominance patterns. It’s not about describing trait distribution across an entire population, which would involve population genetics, nor about determining genetic linkage, which requires mapping of chromosomes. It also doesn’t predict future mutations, since new mutations arise randomly and aren’t specified by parental allele combinations.