Biology Regents 2025 – 400 Free Practice Questions to Pass the Exam

The purpose of a Punnett square is to predict the genotype and phenotype ratios of offspring from a genetic cross between two parents. By using the alleles contributed by each parent, the Punnett square allows one to visualize the possible combinations of alleles that can occur in the offspring. This is particularly useful in genetics when considering traits controlled by single genes, as it helps to illustrate the likelihood of inheriting certain characteristics based on the dominant and recessive alleles present.

For instance, if you know the genotypes of the parents (e.g., one is homozygous dominant and the other is homozygous recessive), you can use the Punnett square to determine the ratio of offspring that will exhibit the dominant phenotype, the recessive phenotype, or heterozygous traits. This predictive nature is essential in genetics for understanding inheritance patterns, such as those observed in Mendelian traits.

In contrast, determining the phenotype of a single organism focuses on the expression of traits and does not involve predicting ratios. Visualizing inheritance in a family pertains more to pedigree analysis than to the specific predictive utility of a Punnett square. Lastly, illustrating genetic mutations in a population does not relate to the function of a Punnett square, as it does not deal