Stem cells can be obtained from bone marrow and used to treat certain blood disorders. Explain how a bone marrow transplant could restore normal blood cell production in a patient whose bone marrow has been destroyed by disease.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Bone marrow contains stem cells that continuously produce blood cells throughout a person's life. In some diseases, the patient's bone marrow is destroyed, meaning they can no longer produce blood cells normally.
Model answer (4 marks)
Bone marrow stem cells are adult stem cells. In a transplant, stem cells from a healthy donor are transferred into the patient.
The transplanted stem cells undergo mitosis, producing more stem cells (self‑renewal).
They then differentiate into the various blood cell types required.
The new stem cells replace the destroyed marrow, restoring normal blood cell production.
The transplanted stem cells undergo mitosis, producing more stem cells (self‑renewal).
They then differentiate into the various blood cell types required.
The new stem cells replace the destroyed marrow, restoring normal blood cell production.
Examiner tips
- Use the exact phrase "adult stem cells" and "self‑renewal" to match the mark scheme.
- Show the sequence: transplant → mitosis → differentiation → restoration.
- Keep the answer concise – 4 marks, one point each.
- Mention the donor source to satisfy the first point.
Common mistakes
- Confusing stem cells with mature blood cells.
- Omitting the step of mitosis or self‑renewal.
- Using vague terms like "new cells" instead of "stem cells".
Mark scheme (4 marks)
- Bone marrow stem cells are adult stem cells / stem cells from a donor are transplanted into the patient
- The transplanted stem cells can divide (by mitosis) to produce more stem cells / self-renew
- The stem cells differentiate into the different types of blood cell needed
- This restores normal blood cell production because the new stem cells carry out the role of the destroyed bone marrow
Key terms in this question
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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