A simple diagram that helps predict genotype and phenotype combinations in genetic crosses is called what?

• A. Punnett Square
• B. Pedigree
• C. Gel Electrophoresis
• D. Karyotype

Answer: (A)

A Punnett square is a simple diagram that shows all possible allele combinations for a cross, letting you predict genotype and phenotype outcomes. You lay out the possible gametes from each parent along the top and side, fill in each cell by combining one allele from each parent, and then read off the resulting genotypes and, with the dominance pattern known, the likely phenotypes. This visual makes it easy to see the probabilities of each outcome—for example, crossing two heterozygotes often yields a 1:2:1 genotype ratio and, depending on dominance, a corresponding phenotype ratio. The other tools have different uses: a pedigree maps inheritance across generations in families, gel electrophoresis separates DNA fragments by size, and a karyotype shows chromosome number and structure. So the diagram that helps predict cross outcomes is the Punnett square.