[Campbell Biology P.527] The 'WHAT IF?' section discusses drug strategies: directly killing ... | Practice Question

The 'WHAT IF?' section discusses drug strategies: directly killing S. aureus or only slowing MRSA growth. Considering natural selection and bacterial gene exchange, why might a strategy that only slows the growth of MRSA be less effective long-term compared to directly killing it?

  • A: Drugs that only slow growth still allow surviving bacteria to reproduce and exchange genes, accelerating the evolution of resistance through natural selection.
  • B: Slowing bacterial growth completely halts gene exchange, making resistance impossible.
  • C: Only drugs that kill *S. aureus* directly can be effective in preventing resistance.
  • D: Bacterial gene exchange only occurs when bacteria are under severe stress from lethal drugs.

Explanation

The 'WHAT IF?' section prompts consideration of natural selection and bacterial gene exchange. If a drug only slows growth, it means a population of S. aureus survives and continues to reproduce. Within this surviving population, natural selection can favor individuals with any degree of resistance, and through rapid reproduction and gene exchange a key feature of bacteria mentioned in the text , resistance can spread and evolve, making the drug less effective over time. Directly killing the bacteria would reduce the pool for resistance to emerge from.