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Infection & ResponseDeep Dive

How Antibiotic Resistance Develops

Part of Antibiotics and Drug Resistance · GCSE GCSE Biology revision

This deep dive covers How Antibiotic Resistance Develops within Antibiotics and Drug Resistance for GCSE Biology. Antibiotic function, bacterial resistance evolution, responsible use, global health impact It is section 5 of 18 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 5 of 18

Practice

23 questions

Recall

12 flashcards

How Antibiotic Resistance Develops

Painted illustration showing how antibiotic resistance evolves. Three Petri dishes in a row: dish 1 shows mostly teal-blue sensitive bacterial colonies plus one red-orange resistant mutant marked with a star (1 in millions). Dish 2 shows the antibiotic disc in the centre with most teal bacteria faded and crossed-out (dead), only the red R surviving. Dish 3 shows the dish filled with red-orange resistant colonies. Below on a painted parchment scroll: 4 numbered mark points (variation, selection pressure, reproduction, population shift). Bottom in red ink: 'Examiner trap — don't say bacteria become resistant; they ARE resistant by mutation, selection just favours them.'

Figure: Natural selection in 3 stages — variation, selection, then a fully resistant population.

The Process of Natural Selection:

  1. Genetic Variation: Random mutations in bacterial DNA create variation in populations
  2. Selection Pressure: When antibiotics are used, they create environmental pressure
  3. Survival of the Fittest: Bacteria with resistance mutations survive while others die
  4. Reproduction: Resistant bacteria multiply and pass resistance genes to offspring
  5. Population Change: Over time, resistant bacteria become dominant in the population

Mechanisms of Resistance:

  • Enzyme Production: Bacteria produce enzymes that break down antibiotics
  • Target Modification: Changes to bacterial structures that antibiotics normally target
  • Efflux Pumps: Bacteria pump antibiotics out of their cells
  • Alternative Pathways: Bacteria develop new metabolic routes to bypass disrupted processes

Keep building this topic

Read this section alongside the surrounding pages in Antibiotics and Drug Resistance. That gives you the full topic sequence instead of a single isolated revision point.

Required Practical: Investigating Antibiotic ActionSuperbugs: The Resistance ChampionsFrom Miracle Cure to Modern CrisisKey Facts About Antibiotics

Practice Questions for Antibiotics and Drug Resistance

What do antibiotics kill or stop growing?

  • A. Viruses
  • B. Bacteria
  • C. Fungi
  • D. All pathogens
1 markfoundation

Explain how antibiotic resistance develops in bacteria through natural selection. (3 marks)

3 marksstandard

Quick Recall Flashcards

Why do antibiotics NOT work against viruses?
Antibiotics target bacterial cell walls and bacterial processes. Viruses do not have cell walls and use the host cell's own machinery to reproduce. There is nothing for the antibiotic to target in a virus.
What are antibiotics and what do they target?
Antibiotics are chemicals that kill bacteria or stop them from growing. They target structures that bacteria have but human cells do not, such as cell walls. Examples: penicillin, amoxicillin, streptomycin.

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Required Practical: Investigating Antibiotic Action

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Superbugs: The Resistance Champions