What is the primary difference between a monohybrid cross and a dihybrid cross?

The primary difference between a monohybrid cross and a dihybrid cross relates to the number of traits being studied and the resulting complexity of the genetic combinations that arise from these traits.

In a monohybrid cross, only one trait is analyzed, which results in a Punnett square that typically has four squares. This setup allows for the examination of allele combinations for a single gene, making the predictions about the offspring’s genotypes and phenotypes straightforward.

Conversely, a dihybrid cross examines two traits simultaneously. This analysis results in a more intricate Punnett square comprising 16 squares, as it accounts for all combinations of alleles from the two different traits. Therefore, the complexity increases because it includes multiple variations of genotype interactions, ultimately reflecting how these traits can be inherited together.

This distinction in the number of traits and complexity of allele combinations is what primarily differentiates the two types of crosses. It shows how genetic principles, such as independent assortment, come into play when more than one trait is considered.