IGCSE›Cambridge IGCSE Biology›Mind mapsDrugsCambridge IGCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsWhat is a drug?Substance that modifies chemical reactions in the bodyInterferes with normal metabolic processesCan be medicinal or recreationalAntibioticsTreat bacterial infections onlyKill or inhibit bacterial cellsSome break down bacterial cell wallsExamples: pneumonia, urinary tract infectionsNot virusesViruses have no cell walls to targetNo effect on colds and fluDoctors do not prescribe them for viral illnessDrugsand antibioticsResistanceBacteria survive antibiotics that normally kill themVariation exists in the bacterial populationSusceptible bacteria die, resistant ones reproducePopulation becomes mostly resistantMRSA is resistant to many antibioticsLimiting resistanceUse antibiotics only when essentialNever use them for viral infectionsComplete the full courseGood hygiene prevents infectionExam tipsDefine a drug as modifying chemical reactions, not just 'medicine'Never say antibiotics kill virusesExplain resistance as natural selection