What is the phenotypic ratio for a dihybrid cross involving two heterozygous parents?

In a dihybrid cross involving two heterozygous parents, the phenotypic ratio observed is 9:3:3:1. This scenario typically examines two traits, each governed by different genes that assort independently.

In this case, both parents are heterozygous for two traits, leading to gametes that combine in various ways during fertilization. The combinations yield a diverse offspring with distinct phenotype ratios. When you construct a Punnett square for a dihybrid cross, the offspring's phenotypes display the following ratios:

• Nine individuals exhibit both dominant traits (A_B_),

• three individuals show the first dominant trait and the recessive trait of the second gene (A_bb),

• three individuals express the recessive trait of the first gene and the dominant trait of the second gene (aaB_),

• and finally, one individual shows both recessive traits (aabb).

When these individual outcomes are tallied, the resulting phenotypic ratio is 9:3:3:1. This classical inheritance pattern illustrates Mendel’s law of independent assortment, which asserts that separate genes for separate traits are passed independently of one another from parents to offspring. Thus, the correct answer confirming the phen