Final answer:
A dihybrid cross following Mendelian genetic laws results in a phenotypic ratio of 9:3:3:1 for unlinked traits, demonstrating Mendel's law of independent assortment and law of segregation in the inheritance of each trait.
Step-by-step explanation:
Mendel's dihybrid crosses involve two traits and provide insight into his laws of inheritance. The offspring from a dihybrid cross will exhibit a 9:3:3:1 phenotypic ratio if the traits are unlinked and assort independently, according to Mendel's law of independent assortment.
In a hypothetical dihybrid cross between two pea plants that are heterozygous for round yellow seeds (RrYy) and wrinkled green seeds (rryy), the expected phenotypic ratio among the offspring would be 9 round yellow:3 round green:3 wrinkled yellow:1 wrinkled green. This outcome demonstrates Mendel's law of independent assortment, showing that each trait is inherited separately from the other. Additionally, the monohybrid cross demonstrates Mendel's law of segregation, where each parent contributes one allele for a given trait to their offspring.