Plasmid-mediated conjugation-theansweris a.genes for drug resistance may reside individually on the bacterial chromo-some or on plasmids. clusters of multiple drug resistance genes are occasionally on chromosomes but are more commonly on plasmids. also, in general, plasmid dna is entirely transferred in a conjugal cross of f+ cells with f cells. r- factors are like those f+ cells with just a few extra, closely linked drug resistance genes. so the conjugal transfer of a r factor is the process that is most likely to transfer multiple drug resistance.