A researcher investigates how the flexibility of a phagocyte's cell membrane affects its ability to destroy bacteria.
Two samples contain the same number of phagocytes. A substance added to sample B only reduces the flexibility of the phagocyte cell membranes. The conditions prevent the bacteria from reproducing during the investigation.
| Sample | Initial number of live bacteria | Number of live bacteria after 20 minutes |
|---|---|---|
| A | 240 | 60 |
| B | 240 | 156 |
Calculate the percentage of bacteria destroyed in each sample. Use your answers and your knowledge of phagocytes to explain why a substance that reduces membrane flexibility could make a bacterial infection more severe.
181 exam-style questions on OCR GCSE Biology 6.3 Monitoring and maintaining health, covering 6.3.1 Health and disease, 6.3.2 Interactions between diseases, 6.3.3 Spread of communicable diseases, 6.3.4 Common infections and diseases, 6.3.5 Physical plant defence responses, 6.3.6 Chemical plant defence responses, 6.3.7 Detecting and identifying plant diseases, 6.3.8 White blood cells and platelets, 6.3.9 Non-specific defence systems, 6.3.10 The immune system, 6.3.11 Monoclonal antibodies, 6.3.12 Vaccines and medicines, 6.3.13 Aseptic techniques, 6.3.14 Discovery and development of new medicines, 6.3.15 Causes of non-communicable diseases, 6.3.16 Treatments for cardiovascular disease, 6.3.17 Lifestyle factors and non-communicable diseases, 6.3.18 Cancer, 6.3.19 Stem cells in medicine, 6.3.20 Gene technology in medicine, and 6.3.21 The human genome and medicine. Each one has a worked solution and a mark scheme showing where the marks go.