What is the phenotype ratio typically observed in a monohybrid cross?

In a monohybrid cross, where two parents differ in a single trait that is controlled by two alleles (one dominant and one recessive), the typical phenotype ratio observed among the offspring is 3:1. This ratio arises from the combination of alleles during fertilization.

When a homozygous dominant individual is crossed with a homozygous recessive individual (for example, a plant that is homozygous for purple flowers crossed with one that is homozygous for white flowers), all the first generation (F1) offspring will display the dominant phenotype. If those F1 individuals are then crossed with each other, the resulting F2 generation exhibits a mix of phenotypes. Specifically, three out of four offspring display the dominant trait, while one out of four displays the recessive trait. Therefore, the phenotype ratio of the F2 generation is 3:1, which accurately represents the expected outcomes in a monohybrid cross.

This pattern illustrates the basic principles of Mendelian genetics, specifically demonstrating the segregation of alleles during gamete formation and fertilization. Understanding this ratio is crucial for predicting inheritance patterns in future generations.