A scientist is researching stem cells to develop new treatments for diseases. Explain why stem cells are useful in medicine and describe how they can be used to treat patients with damaged tissues.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Stem cells are unspecialised cells found in embryos and in some adult tissues. Researchers believe stem cells could be used to replace damaged or diseased cells in a range of medical conditions, including those affecting the nervous system and blood.
Model answer (5 marks)
Stem cells are unspecialised, undifferentiated cells that can divide and give rise to many different specialised cell types.
Because of this, they can be used to replace damaged or diseased cells or tissues in the body.
Embryonic stem cells are pluripotent – they can differentiate into any cell type, whereas adult stem cells (e.g. bone‑marrow stem cells) can give rise to blood cells.
In medicine, stem cells are therefore grown or activated in the laboratory and then transplanted into patients to regenerate damaged tissue, such as bone‑marrow transplants for leukaemia or neural stem cells for spinal‑cord injury.
However, the use of embryonic stem cells raises ethical concerns about the destruction of embryos, and all stem‑cell therapies carry risks of rejection, infection or tumour formation.
Because of this, they can be used to replace damaged or diseased cells or tissues in the body.
Embryonic stem cells are pluripotent – they can differentiate into any cell type, whereas adult stem cells (e.g. bone‑marrow stem cells) can give rise to blood cells.
In medicine, stem cells are therefore grown or activated in the laboratory and then transplanted into patients to regenerate damaged tissue, such as bone‑marrow transplants for leukaemia or neural stem cells for spinal‑cord injury.
However, the use of embryonic stem cells raises ethical concerns about the destruction of embryos, and all stem‑cell therapies carry risks of rejection, infection or tumour formation.
Examiner tips
- Use the term ‘undifferentiated’ and ‘pluripotent’ where appropriate
- Show the link between differentiation and replacement of damaged tissue
- Mention both embryonic and adult stem cells and give a specific example of a treatment
- Include the ethical/risks point to cover all marks
Common mistakes
- Confusing stem cells with mature cells, or omitting the term ‘undifferentiated’
- Failing to name a specific medical application, e.g. bone‑marrow transplant
- Leaving out the ethical issue or the risk of rejection/infection
Mark scheme (5 marks)
- Stem cells are unspecialised / undifferentiated cells
- Stem cells can differentiate into many / different types of specialised cells
- Stem cells can be used to replace damaged or diseased cells / tissues in the body
- Embryonic stem cells can differentiate into any cell type (are pluripotent) OR adult stem cells are found in bone marrow and can differentiate into blood cells
- There are ethical concerns / risks associated with stem cell use, e.g. use of embryos raises ethical issues OR risk of rejection / infection
Key terms in this question
Related
- All OCR A-Level Biology B — Advancing Biology (H422) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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