Knowledge Organiser
Part of Antibiotics and Drug Resistance · GCSE GCSE Biology revision
This topic summary covers Knowledge Organiser within Antibiotics and Drug Resistance for GCSE Biology. Antibiotic function, bacterial resistance evolution, responsible use, global health impact It is section 17 of 18 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 17 of 18
Practice
23 questions
Recall
12 flashcards
Knowledge Organiser
Natural Selection Steps
- Random mutation gives resistance to one bacterium
- Antibiotic = selection pressure
- Non-resistant bacteria killed
- Resistant bacteria survive and reproduce
- Offspring inherit resistance gene
- Resistant strain becomes dominant
How Antibiotics Work
- Penicillin: blocks cell wall synthesis → cell bursts
- Streptomycin: blocks bacterial ribosomes → no protein synthesis
- Only affect bacteria — viruses have no cell wall or bacterial ribosomes
- MRSA: resistant to methicillin + many others
- Disc diffusion: larger zone = more effective
Common Marks Lost
- "Person becomes resistant" — bacteria become resistant, not people
- "Bacteria learn" — random mutation, not deliberate adaptation
- Missing "mutation" in natural selection answers
- Not explaining WHY completing course reduces resistance
- Saying antibiotics kill viruses (they do not)
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.
Practice Questions for Antibiotics and Drug Resistance
What do antibiotics kill or stop growing?
Explain how antibiotic resistance develops in bacteria through natural selection. (3 marks)
Quick Recall Flashcards
23 questions on Antibiotics and Drug Resistance — practise free
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