# A doctor is considering two types of stem cell therapy to treat a patient who has developed a degenerative nerve disease. The doctor is deciding between using adult stem cells taken from the patient's own bone marrow and using embryonic stem cells. Explain why embryonic stem cells and adult stem cells differ in their potential to treat this disease, and suggest one ethical issue associated with using embryonic stem cells.

> Pearson Edexcel A-Level Biology A (9BI0) — 2.1 Stem cells and cell potency · Explain · 5 marks

> Degenerative nerve diseases destroy specialised neurones in the central nervous system over time. Scientists are investigating stem cell therapies that could replace the lost neurones.

## Mark scheme (5 marks)

1. Embryonic stem cells can differentiate into any cell type (are totipotent/pluripotent)
2. Therefore embryonic stem cells could be directed to differentiate into neurones / nerve cells to replace those lost
3. Adult stem cells can only differentiate into a limited range of cell types
4. Therefore adult stem cells from bone marrow may not be able to differentiate into the required neurones / nerve cells
5. One valid ethical issue related to using embryonic stem cells, e.g. the embryo is destroyed in the process / the embryo is a potential human life / religious or moral objections to destroying embryos

## Key terms

- [embryonic stem cells](https://www.gradenine.co.uk/glossary/embryonic-stem-cells)
- [adult stem cells](https://www.gradenine.co.uk/glossary/adult-stem-cells)

## Related

- [Revision notes for Pearson Edexcel A-Level Biology A (9BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-doctor-is-considering-two-types-1dcb4a4d) · Published by Druglandscape Ltd.