Stem cells can be used in medicine to treat a range of diseases. Evaluate the use of embryonic stem cells as a medical treatment.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
1. Embryonic stem cells can differentiate into any cell type, so they can repair damaged tissues in a wide range of diseases such as Parkinson’s, spinal cord injury and diabetes.
2. Because they are pluripotent, they are not recognised as foreign by the immune system, so matching to the patient is unnecessary and rejection is unlikely.
3. However, obtaining them requires destruction of the embryo, which raises significant ethical objections and limits public acceptance.
4. In the laboratory, stem cells may become contaminated or acquire mutations; if these are transferred to the patient they could cause tumour formation or other complications.
5. Finally, the therapy is still experimental; long‑term safety and efficacy are unknown, and there is no guarantee that the treatment will succeed.
2. Because they are pluripotent, they are not recognised as foreign by the immune system, so matching to the patient is unnecessary and rejection is unlikely.
3. However, obtaining them requires destruction of the embryo, which raises significant ethical objections and limits public acceptance.
4. In the laboratory, stem cells may become contaminated or acquire mutations; if these are transferred to the patient they could cause tumour formation or other complications.
5. Finally, the therapy is still experimental; long‑term safety and efficacy are unknown, and there is no guarantee that the treatment will succeed.
Examiner tips
- Use the exact terms ‘pluripotent’, ‘immune rejection’, ‘ethical issues’, ‘contamination/mutation’, and ‘long‑term risks’. Show a clear balance of benefits and risks, matching the five points. Keep each point concise and to the point.
- Use bullet‑style numbering or short sentences to show each point clearly.
Common mistakes
- Mixing up embryonic with adult stem cells. Failing to mention the ethical issue of embryo destruction. Over‑emphasising benefits without acknowledging risks.
Mark scheme (5 marks)
- Benefit: stem cells can be used to treat a large variety of different diseases / repair damaged tissues
- Benefit: stem cells are not rejected / do not need to be matched to the patient unlike donor organs
- Risk: embryos are destroyed in the process of harvesting the stem cells, raising ethical issues
- Risk: stem cells could be contaminated or mutated whilst being grown in the laboratory, which could be passed on to the patient
- Risk: stem cell therapy is relatively new so long-term risks are unknown / no guarantee the treatment will work
Key terms in this question
Related
- All Eduqas A-Level Biology revision notes →
- How to answer a "Evaluate" question →
- Decode the mark scheme abbreviations →
More Cell structure and organisation questions
- Explain why prokaryotic cells, such as bacteria, are different from eukaryotic c…
- Describe the roles of mitosis and cell differentiation in the growth and develop…
- Explain how the structure of an enzyme allows it to carry out its function, and …
- Meiosis and mitosis are both types of cell division that occur in the human body…