Final answer:
A Punnett square is a tool used in genetics to predict the likelihood of genotypes in the offspring from two parents' genetic alleles. It is especially useful for illustrating monohybrid crosses, showing dominant and recessive allele interactions.
Step-by-step explanation:
A Punnett square is a diagram that predicts the probability of the offspring's genotypes based on the genetic alleles of the parents. For example, if we have two parents with purple flowers that are heterozygous (Pp), the Punnett square would show a possible genetic outcome ratio for their offspring. Each parent's alleles are listed on respective sides of the grid, and the interior squares reveal the potential combinations for offspring, demonstrating their expected frequencies. Dominant alleles, like 'P', will mask the expression of recessive alleles such as 'p'.
In a monohybrid cross like the one described, the Punnett square shows each possible combination of these alleles, allowing the estimation of genotypic ratios, which in turn inform us of the phenotypic ratios—the visible characteristics depending on dominant or recessive traits. However, when considering complex traits involving more genes, methods such as the forked-line or probability approaches become more practical due to the exponential increase in possible genetic combinations.