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

In a monohybrid cross, where two individuals differing in a single trait are crossed, the expected phenotypic ratio among the offspring in the F2 generation is 3:1. This occurs due to the segregation of alleles during gamete formation and the combination of these alleles when gametes fuse during fertilization.

In the F1 generation, all offspring typically display the dominant phenotype since they receive one dominant allele from each parent. When these F1 individuals are intercrossed (F1 x F1), the resulting F2 generation has a chance to inherit different combinations of the alleles. The possible combinations of alleles result in one homozygous dominant (dominant phenotype), two heterozygous (also dominant phenotype), and one homozygous recessive (recessive phenotype) offspring. Thus, out of a total of four possible phenotypes, three exhibit the dominant characteristic and one exhibits the recessive, leading to the classic 3:1 ratio.

This ratio reflects the basic principles of Mendelian inheritance as formulated by Gregor Mendel in his experiments with pea plants.