A scientist is comparing two types of stem cells. Explain the differences between embryonic stem cells and adult stem cells, and suggest why embryonic stem cells are considered more useful for medical treatments.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Stem cells are used in medical research and treatment. Scientists can obtain stem cells from two main sources: early embryos and bone marrow.
Model answer (5 marks)
Embryonic stem cells are pluripotent – they can differentiate into any cell type in the body. Adult stem cells, such as those from bone marrow, are multipotent – they can only give rise to a limited range of cell types. Both types are undifferentiated and capable of differentiation. Because embryonic stem cells can produce a wider variety of specialised cells and tissues, they are more useful for medical treatments, whereas adult stem cells are restricted in the range of cells they can generate.
Examiner tips
- Use the terms pluripotent and multipotent to show understanding of differentiation capacity.
- Explain the practical advantage of a wider range of cell types for therapy.
- Show the limitation of adult stem cells in the answer.
Common mistakes
- Confusing pluripotent with totipotent; totipotent refers to zygote only.
- Saying adult stem cells can become any cell type – they are not pluripotent.
- Omitting the key point that embryonic cells can produce a wider range of specialised cells.
Mark scheme (5 marks)
- Embryonic stem cells can differentiate into any cell type (are pluripotent)
- Adult stem cells are found in bone marrow and can only form many (but not all) types of cells
- Both are undifferentiated / unspecialised cells capable of differentiating
- Embryonic stem cells are more useful because they can be used to produce a wider range of specialised cells / tissues for treatment
- Adult stem cells are limited in the range of cell types they can produce, making them less versatile for medical treatments
Key terms in this question
embryonic stem cell · adult stem cell
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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