In a genetic cross, if a trait is determined to be dominant, what is the expected ratio in the F2 generation?

When a trait is determined to be dominant, the expected phenotypic ratio in the F2 generation typically follows the principles of Mendelian inheritance as elucidated through monohybrid crosses.

In a monohybrid cross, two heterozygous parent organisms (for example, Aa x Aa) are considered. Each parent can contribute either a dominant (A) or recessive (a) allele to the offspring. The potential combinations of alleles in the F2 generation can be represented as follows:

1. AA (homozygous dominant)

2. Aa (heterozygous)

3. aA (heterozygous, but genetically identical to Aa)

4. aa (homozygous recessive)

When the offspring's phenotypes are analyzed based on these genotypes, the dominant phenotype (both AA and Aa) will appear more frequently than the recessive phenotype (aa). Specifically, the dominant phenotype is expressed in 3 of the 4 possible combinations (AA, Aa, and aA), while the recessive phenotype is expressed only in 1 combination (aa).

Thus, the phenotypic ratio in the F2 generation is expected to be 3 dominant to