A patient with a degenerative joint condition is told that doctors could use stem cells from bone marrow to help repair the damaged tissue. Explain why bone marrow stem cells can be used in this way, and describe ONE limitation of using this type of stem cell compared to embryonic stem cells.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Researchers are investigating the use of stem cells to treat a range of diseases. Bone marrow transplants have been used for decades, but scientists continue to debate the relative merits of different stem cell sources.
Model answer (5 marks)
Bone marrow stem cells are adult stem cells, which can divide and give rise to specialised cells.
1. They can differentiate into the cell types needed for bone and cartilage repair.
2. As adult stem cells they are already committed to the mesodermal lineage.
3. They can produce osteoblasts, chondrocytes and other bone‑forming cells.
4. However, adult stem cells have a limited potency – they can only become a restricted range of cell types.
5. This is a limitation compared to embryonic stem cells, which are pluripotent and can generate any cell type, so bone‑marrow cells may not be able to produce the exact cell type required for full tissue regeneration.
1. They can differentiate into the cell types needed for bone and cartilage repair.
2. As adult stem cells they are already committed to the mesodermal lineage.
3. They can produce osteoblasts, chondrocytes and other bone‑forming cells.
4. However, adult stem cells have a limited potency – they can only become a restricted range of cell types.
5. This is a limitation compared to embryonic stem cells, which are pluripotent and can generate any cell type, so bone‑marrow cells may not be able to produce the exact cell type required for full tissue regeneration.
Examiner tips
- Use the term ‘adult stem cells’ and ‘differentiation’ early. Show the limited range of cell types they can become. Contrast with the ‘pluripotent’ nature of embryonic cells. Explain the limitation clearly in one sentence.
Common mistakes
- Calling bone‑marrow cells embryonic stem cells. Forgetting to mention the limited potency of adult stem cells. Using vague terms like ‘can become many cells’ instead of specifying the restricted range.
Mark scheme (5 marks)
- Bone marrow stem cells are adult stem cells
- Adult stem cells can undergo cell differentiation to become specialised cell types
- Adult stem cells can differentiate into a limited range of cell types (e.g. blood cells or bone cells)
- Embryonic stem cells can differentiate into any cell type (are less restricted / more potent)
- This is a limitation because adult stem cells may not be able to differentiate into the specific cell type needed to repair the damaged tissue / they have a limited range compared to embryonic stem cells
Key terms in this question
Related
- All Edexcel A-Level Biology A: Salters-Nuffield (9BN0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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