Question
A patient has leukaemia (blood cancer). Doctors propose a bone marrow transplant from a matched donor.
Explain how stem cells from the donor could treat the patient, and discuss benefits and risks. [6]
Mark scheme — level 3 (5–6): mechanism + ≥1 benefit + ≥1 risk clearly linked.
- Bone marrow contains haematopoietic (adult) stem cells (B1)
- These differentiate into all types of blood cells (B1)
- Donor cells replace the patient's diseased/destroyed bone marrow cells (B1)
- Benefit: restores normal blood cell production / long-term cure possible (B1)
- Risk: donor and patient must be tissue-matched to reduce rejection (B1)
- Risk: patient's immune system must be suppressed before transplant, increasing infection risk (B1)
6 marks · take your time before peeking.
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Generated by TopMyGrade AI · cross-check official sources before relying on the mark-scheme phrasing.