Practice question

Dihybrid cross analyses two independent characters simultaneously, such as seed shape and seed colour, each controlled by separate locus. Parental true-breeding lines differ in both traits, F1 diheterozygotes generate four gamete classes via independent assortment or recombination. Selfing produces sixteen combinations, collapsing to phenotypic ratio 9:3:3:1 under dominance and independence. Concept tests second law, differentiates linkage from unlinked behaviour and reveals epistatic interactions. One character or one gene defines monohybrid, two alleles only insufficient descriptor for two-locus segregation pattern. Conceptual clarity supports solving numerical problems involving segregation ratios, recombination frequencies and probability calculations in crosses.