Final answer:
A Punnett square is utilized to predict the possible genetic combinations and their outcomes from a simple genetic cross; it applies probability rules to determine genotypic and phenotypic ratios.
Step-by-step explanation:
A Punnett square can be used to predict the outcome of a simple genetic cross. The Punnett square, named after the British geneticist Reginald Punnett, applies the rules of probability to forecast the possible genetic combinations from the mating of two parents. Each parent contributes their alleles, and every combination is depicted in the grid of the Punnett square to determine the genotypic ratios. If the pattern of inheritance for the dominant and recessive traits is known, phenotypic ratios can also be calculated. In the case of a monohybrid cross involving true-breeding pea plants with dominant yellow seeds and recessive green seeds (genotypes YY and yy, respectively), all resulting offspring would have the genotype Yy, expressing the dominant yellow seed phenotype.