In a dihybrid cross, what is the expected phenotypic ratio?

In a dihybrid cross, which involves two traits, the expected phenotypic ratio is 9:3:3:1. This ratio reflects the combinations of two independently assorting traits, each represented by alleles from two parents that are both heterozygous for those traits.

When conducting a dihybrid cross, such as between two individuals that are both heterozygous for two traits (e.g., AaBb x AaBb), you can set up a Punnett square that illustrates how the alleles combine in the offspring. Each trait behaves independently due to Mendel's law of independent assortment. As a result, when you calculate the potential combinations of traits, you will find that:

• 9 offspring will exhibit the dominant traits for both traits,

• 3 offspring will show the dominant trait of the first trait and the recessive trait of the second,

• 3 offspring will show the recessive trait of the first trait and the dominant trait of the second,

• 1 offspring will exhibit the recessive traits for both traits.

This results in the 9:3:3:1 ratio, which is characteristic of a dihybrid cross where both parents are heterozygous for two traits. This