Question

Sol.(a) [Key Concept: Gene Interaction — Polymeric Genes Ratio] A 9:6:1 F2 ratio is obtained in case of POLYMERIC GENES (duplicate dominant gene interaction). When two genes produce similar effects and either dominant allele alone gives one phenotype, AABB gives another, and aabb gives yet another, the ratio is 9(A_B_):6(A_bb + aaB_):1(aabb). This is a modification of the standard 9:3:3:1 ratio where 3+3=6 classes merge. Examples: fruit shape in shepherd's purse.