In a Punnett square, what do the rows and columns represent?

• A. The gametes produced by each parent.
• B. The chromosomes in a cell.
• C. The environmental influences on expression.
• D. The phenotypes of the offspring.

Answer: (A)

In a Punnett square, the rows and columns represent the gametes each parent can contribute. Each row lists the possible gametes from one parent, and each column lists the possible gametes from the other parent. By pairing a row with a column, you determine the genotype of the offspring for that combination of parental gametes, showing all potential genetic outcomes for a trait with two alleles. The other options don’t fit because chromosomes are the actual cellular carriers, environmental influences affect expression rather than the gamete combinations, and phenotypes are the expressed traits—not the combinations shown in the grid.