Practice question

Recombination frequency measures proportion recombinant chromatids among total chromatids examined. For two markers, even when unlinked and assorting independently, maximum half chromatids become recombinant because random chromatid involvement and independent orientation yields equal parental and recombinant recovery. In tetrads formula with TT divided two plus NPD over total cannot exceed 0.5 × total, corresponding 50 percent or 50 centimorgans limit ceiling. Higher crossover numbers generate parental restoration via double exchanges involving same chromatids, keeping RF at 50 percent ceiling equivalent random segregation expectation for unlinked loci.