Antibiotic resistance refers to which concept?

• A. The evolution of populations of pathogenic bacteria that antibiotics are unable to kill
• B. A temporary tolerance to antibiotics
• C. Bacteria producing antibiotics to kill other bacteria
• D. The complete destruction of antibiotics by bacteria

Answer: (A)

Antibiotic resistance is the evolutionary process by which bacterial populations adapt so that an antibiotic no longer inhibits their growth or kills them. When a drug is used, it creates selective pressure: some bacteria carry mutations or acquire genes that reduce the drug’s effectiveness, survive, and pass those traits to their offspring. Over time, these resistant traits become common, and the population can thrive despite the antibiotic. This is a heritable, population-level change driven by natural selection and can spread between bacteria.

Why this is the best description: it captures that resistance is not just a temporary tolerance, nor simply bacteria making antibiotics or completely destroying drugs. It’s about heritable changes that allow survival in the presence of an antibiotic, leading to a shift in the population toward resistant strains.