In a typical Mendelian dihybrid cross, what is the ratio of phenotypes in the offspring?

In a typical Mendelian dihybrid cross, the phenotypes of the offspring follow a 9:3:3:1 ratio. This ratio arises from a genetic scenario where two traits are being considered, each determined by different alleles at two separate loci.

When we cross two individuals that are heterozygous for both traits (e.g., AaBb x AaBb), we establish a scenario where each parent can produce four types of gametes due to independent assortment: AB, Ab, aB, and ab. These gametes combine in specific ways during fertilization to create various combinations of alleles in the offspring.

The resulting phenotype combinations can be analyzed to determine the ratios of the different phenotypes present:

• Nine offspring exhibit the dominant trait for both characteristics,
• Three offspring exhibit the dominant trait for one characteristic and the recessive trait for the other,
• Three offspring exhibit the recessive trait for one characteristic and the dominant trait for the other,
• One offspring exhibits the recessive trait for both characteristics.

This detailed interaction between the genes results in a 9:3:3:1 phenotypic ratio, reflecting the diversity of combinations that can arise from independent assortment during gamete formation and fertilization in a di