In monohybrid inheritance, the number of phenotypic classes in F2 is
In monohybrid inheritance with complete dominance, F2 generation from Tt selfing shows three genotypes TT, Tt and tt but collapses into two phenotypic classes dominant tall comprising TT and Tt and recessive dwarf tt. Number of phenotypic classes therefore two. Single class would indicate fixation, three classes implies incomplete dominance or codominance with distinct heterozygous phenotype, four classes correspond to dihybrid phenotypic array 9:3:3:1. Dominance interaction reduces genotypic diversity to binary phenotypic distinction central to Mendelian monohybrid analysis. Cytological corre
Ref: Pierce, Genetics, 7th ed., Chapter 3: Phenotypic Classes F2