Explain why studying the brain is extremely difficult for scientists trying to understand and cure diseases such as Alzheimer's and Parkinson's disease.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Research into the structure and functions of the brain could have a huge impact on our ability to cure diseases such as Alzheimer's and Parkinson's disease. In many of these diseases, nerve cells in the cerebral cortex begin to die, leading to a decrease in functionality.
Model answer (5 marks)
The brain contains billions of neurons, making it extremely complex to study.
The brain must still be working – the patient must be alive – for many functions to be studied.
There are ethical issues because patients with brain damage may not be able to give informed consent.
Studies are only carried out after damage has occurred, so it cannot be compared to the healthy brain – a baseline is absent.
Brain damage rarely causes a single problem, making it difficult to match specific problems to specific damaged neurons or areas.
The brain must still be working – the patient must be alive – for many functions to be studied.
There are ethical issues because patients with brain damage may not be able to give informed consent.
Studies are only carried out after damage has occurred, so it cannot be compared to the healthy brain – a baseline is absent.
Brain damage rarely causes a single problem, making it difficult to match specific problems to specific damaged neurons or areas.
Examiner tips
- Use the exact wording from the mark scheme – e.g. ‘billions of neurons’, ‘must still be working’, ‘ethical issues’, ‘baseline is absent’, ‘rarely causes a single problem’.
- Show the five points in a clear, numbered list or separate sentences.
- Keep the answer concise – 5 marks, so one sentence per point is enough.
Common mistakes
- Writing extra information not asked for, such as details of Alzheimer’s pathology.
- Using vague terms like ‘complex’ without mentioning billions of neurons.
Mark scheme (5 marks)
- The brain contains billions of neurones, making it extremely complex to study
- The brain must still be working / the patient must be alive for many functions to be studied
- There are ethical issues because patients with brain damage may not be able to give informed consent
- Studies are only carried out after damage has occurred so it cannot be compared to the healthy brain / a baseline is absent
- Brain damage rarely causes a single problem, making it difficult to match specific problems to specific damaged neurones / areas
Related
- All WJEC A-Level Biology (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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