Some people suffer from a chronic skin condition called eczema, which causes itchy, inflamed skin flare-ups. Scientists have developed a treatment containing an antibody that targets a cell-surface protein associated with skin inflammation.
Complete these sentences to describe how the immune system responds to foreign cells in the body.
Use words from the list. Each word can be used once, more than once, or not at all.
Foreign cells have chemical groups on their surface called ____________.
These chemical groups are detected by certain ____________ which then produce specific antibodies.
Doctors test this new antibody cream on eczema patients.
The patients are divided into two groups:
They record the mean number of days per month that each patient suffers from itchy skin flare-ups before and after the treatment.
The table below shows their results.
| Treatment | Mean number of flare-up days per patient before treatment | Mean number of flare-up days per patient after treatment | Percentage decrease in flare-up days per patient |
|---|---|---|---|
| antibody cream | 12.5 | 5.0 | 60.0% |
| placebo cream | 12.5 | 8.0 | 36.0% |
The placebo group does not receive the active antibody cream.
Suggest why this group is included in the clinical trial.
The total number of flare-up days for all patients in the placebo group after treatment was 640.
The mean number of flare-up days per patient in the placebo group after treatment was 8.0.
Calculate the total number of patients in the placebo group.
Explain why it is important that independent scientists repeat this clinical trial.
97 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.