A laboratory investigates the effect of an antibiotic on a bacterial culture. The number of bacteria is measured at the start and after 24 hours.
| Culture | Number of bacteria at start (per cm³) | Number of bacteria after 24 hours (per cm³) |
|---|---|---|
| With antibiotic | 2.4 × 10⁶ | 6.0 × 10⁵ |
| Without antibiotic | 2.4 × 10⁶ | 8.5 × 10⁸ |
Calculate the percentage decrease in the number of bacteria in the culture with antibiotic after 24 hours.
Explain what the results suggest about using this antibiotic to treat a bacterial infection, and why it would not treat a viral infection.
87 exam-style questions on Edexcel GCSE Biology 5.3 Immune system and medicines, covering 5.3.1 The specific immune system, 5.3.2 Response to immunisation, 5.3.3 Advantages and disadvantages of immunisation, 5.3.4 Antibiotics and bacterial infections, 5.3.5 Aseptic techniques in culturing, 5.3.6 Cross-sectional areas of cultures, 5.3.7 Stages of developing new medicines, and 5.3.8 Production of monoclonal antibodies. Each one has a worked solution and a mark scheme showing where the marks go.