Stem Cells and Their Uses — AQA GCSE Biology

Stem cells are undifferentiated cells that can divide and form other types of cell. They have important medical and agricultural uses.

What are stem cells?

A stem cell is an undifferentiated cell that can:

Embryonic stem cells — found in early embryos; can differentiate into any type of cell.
Adult stem cells — found in some adult tissues (e.g. bone marrow); can form a limited range of cell types, such as blood cells.
Plant stem cells — found in meristems (root and shoot tips); can differentiate throughout the plant's life.

Medicine: stem cells may treat conditions such as diabetes (producing insulin-making cells) and paralysis (replacing nerve cells).
Therapeutic cloning produces an embryo with the same genes as the patient, so the stem cells are not rejected by the immune system.
Plants: meristem stem cells are used to produce large numbers of identical plants (clones) quickly and cheaply — useful for rare species or disease-resistant crops.

Risks: stem cells grown in a lab could be infected with a virus and passed to the patient.
Ethical issues: some people object to using embryos, as they could develop into a person.

You should be able to discuss the benefits and objections.

Define a stem cell as undifferentiated with the ability to divide and differentiate.
Embryonic → any cell type; adult → limited range; plant (meristem) → throughout life.
Explain therapeutic cloning and why it avoids rejection.
Be ready to give both sides of the ethical debate.