What is the phenotypic ratio expected in a dihybrid cross for two traits?

What is the phenotypic ratio expected in a dihybrid cross for two traits?

• A. 3:1
• B. 1:2:1
• C. 9:3:3:1
• D. 2:1

Answer: (C)

In a dihybrid cross, where two traits are considered simultaneously, the expected phenotypic ratio is 9:3:3:1. This ratio arises when each trait follows Mendelian inheritance mechanisms and involves two heterozygous parents (typically represented as AaBb x AaBb, where A and a represent alleles for one trait and B and b for another trait). The 9:3:3:1 phenotypic ratio can be broken down as follows: - The "9" represents the individuals showing both dominant traits (A-B-). - The "3" represents individuals with the dominant trait for the first characteristic and recessive for the second (A-bb). - The second "3" corresponds to individuals with the recessive trait for the first characteristic while having the dominant trait for the second (aaB-). - The "1" reflects individuals that have the recessive traits for both characteristics (aabb). This 9:3:3:1 ratio is significant in genetics as it illustrates the independent assortment of alleles during gamete formation, leading to the varied combinations expressed in the offspring. In contrast, the other ratios pertain to different genetic scenarios: a 3:1 ratio is

In a dihybrid cross, where two traits are considered simultaneously, the expected phenotypic ratio is 9:3:3:1. This ratio arises when each trait follows Mendelian inheritance mechanisms and involves two heterozygous parents (typically represented as AaBb x AaBb, where A and a represent alleles for one trait and B and b for another trait).

The 9:3:3:1 phenotypic ratio can be broken down as follows:

• The "9" represents the individuals showing both dominant traits (A-B-).

• The "3" represents individuals with the dominant trait for the first characteristic and recessive for the second (A-bb).

• The second "3" corresponds to individuals with the recessive trait for the first characteristic while having the dominant trait for the second (aaB-).

• The "1" reflects individuals that have the recessive traits for both characteristics (aabb).

This 9:3:3:1 ratio is significant in genetics as it illustrates the independent assortment of alleles during gamete formation, leading to the varied combinations expressed in the offspring. In contrast, the other ratios pertain to different genetic scenarios: a 3:1 ratio is