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Infection & ResponseRequired Practical

Required Practical: Investigating Antibiotic Action

Part of Antibiotics and Drug Resistance · GCSE GCSE Biology revision

This required practical covers Required Practical: Investigating Antibiotic Action within Antibiotics and Drug Resistance for GCSE Biology. Antibiotic function, bacterial resistance evolution, responsible use, global health impact It is section 4 of 18 in this topic. Revise both the method and the reason for each step, because practical questions often test understanding rather than pure recall.

Topic position

Section 4 of 18

Practice

23 questions

Recall

12 flashcards

🧪 Required Practical: Investigating Antibiotic Action

Disc Diffusion Method

Aim: To investigate the effectiveness of different antibiotics against bacterial growth

Method:

  1. Prepare sterile agar plates
  2. Spread bacterial culture evenly across the plate
  3. Place antibiotic discs on the surface
  4. Incubate at 25°C for 24-48 hours
  5. Measure zones of inhibition around each disc

Results Interpretation:

  • Large zone: Antibiotic is very effective
  • Small zone: Antibiotic has limited effectiveness
  • No zone: Bacteria are resistant to the antibiotic

Aseptic Techniques:

  • Work near a Bunsen burner flame for sterile updraft
  • Flame bottle necks before and after use
  • Use sterile equipment (autoclave sterilization)
  • Handle petri dish lids carefully - don't lift fully
  • Seal plates with tape after inoculation

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.

How Antibiotics Work: Mechanisms of ActionHow Antibiotic Resistance DevelopsFrom 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

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.
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.

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How Antibiotics Work: Mechanisms of Action

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How Antibiotic Resistance Develops