What is the expected phenotypic ratio in the F2 generation of a typical monohybrid cross?

In a typical monohybrid cross, a single trait controlled by one gene with two alleles is examined. When two homozygous parents are crossed (one with a dominant allele and one with a recessive allele), the F1 generation consists entirely of heterozygous offspring, displaying the dominant phenotype.

When these F1 individuals are then crossed with one another, in the F2 generation, the offspring will show a variety of genotypes: homozygous dominant, heterozygous, and homozygous recessive. The resulting genotypic combinations will lead to a phenotypic ratio where three offspring will display the dominant phenotype for every one offspring that displays the recessive phenotype. This means the expected phenotypic ratio in the F2 generation is 3:1, representing three individuals exhibiting the dominant trait for every one individual exhibiting the recessive trait. This classic ratio arises from the principle of segregation and random fertilization outlined by Mendelian genetics, where dominant traits mask the expression of recessive ones.