Punnett Square is a diagram used to do which of the following?

• A. Predict the outcome of a cross to determine the probability of offspring having a particular genotype
• B. Show the energy flow in a cell
• C. Map the locations of genes on a chromosome
• D. Describe gene expression rates

Answer: (A)

Punnett squares are used to predict genetic outcomes of a cross by showing the possible allele combinations in offspring and the probabilities of different genotypes (and thus phenotypes). By placing the possible gametes from each parent on the sides of the grid and filling in each cell, you can see every potential genotype and how likely each one is. This makes it a practical way to understand inheritance patterns under Mendel’s rules, rather than just guessing. For example, crossing two heterozygous individuals for a dominant-recessive trait typically results in a 1:2:1 genotype ratio (and a 3:1 phenotype ratio if the trait is dominant). It’s not about energy flow in a cell, mapping gene locations on a chromosome, or measuring gene expression rates, which are addressed by different concepts.