A scientist is researching a new antifungal medicine extracted from soil bacteria. Explain why the scientist must test the medicine for purity and carry out clinical trials before it can be approved for use in patients.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Soil bacteria produce a range of chemical compounds, some of which have been found to have medicinal properties. One such compound is being investigated as a potential antifungal medicine. Before it can be prescribed to patients, it must pass through several stages of testing and approval.
Model answer (5 marks)
The medicine must be tested for purity to ensure it does not contain harmful impurities or contaminants.
Clinical trials are carried out to test that the medicine is safe for use in humans.
Clinical trials also test that the medicine is effective and works as intended against the fungal infection.
A placebo is used in trials so that results can be compared to patients receiving no active treatment, determining whether any improvement is due to the medicine itself.
The trial and approval process ensures that the benefits of the medicine outweigh the risks before it is approved for widespread use.
Clinical trials are carried out to test that the medicine is safe for use in humans.
Clinical trials also test that the medicine is effective and works as intended against the fungal infection.
A placebo is used in trials so that results can be compared to patients receiving no active treatment, determining whether any improvement is due to the medicine itself.
The trial and approval process ensures that the benefits of the medicine outweigh the risks before it is approved for widespread use.
Examiner tips
- Use the exact phrases from the mark scheme – e.g. ‘purity’, ‘clinical trials’, ‘placebo’. Show the logical sequence: purity → safety → efficacy → comparison with placebo → risk/benefit assessment. Keep each point short and to the point, matching the 5 marks.
- common_mistakes
- :
- Mixing up the order of points or omitting the placebo element. Using vague language such as ‘testing’ instead of ‘purity’ or ‘clinical trials’.
Mark scheme (5 marks)
- The medicine must be tested for purity to ensure it does not contain harmful impurities / contaminants
- Clinical trials are carried out to test the medicine is safe for use in humans
- Clinical trials test that the medicine is effective / works as intended against the condition
- A placebo is used in trials so that results can be compared to patients receiving no active treatment, to determine whether any improvement is due to the medicine itself
- The trial/approval process ensures the benefits of the medicine outweigh the risks before it is approved for widespread use
Key terms in this question
Related
- All OCR A-Level Chemistry B: Salters (H433) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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