Stem cells in medicine

Structure and functions in living organisms · Cells and levels of organisation · note 4 of 4

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In short

Stem cells are cells that have not yet differentiated, so they can develop into different types of cell and may replace damaged or diseased cells, for example to treat diabetes or paralysis. Embryonic stem cells can become almost any cell type. Risks include tumours, passing on viruses, rejection by the immune system and ethical objections to using embryos.

Stem cells are cells that have not yet differentiated, so they can develop into different types of cell. They may be able to replace damaged or diseased cells. Possible uses include treating conditions such as diabetes and paralysis, and replacing damaged tissue.

Embryonic stem cells come from early embryos and can develop into almost any type of cell. Adult stem cells, for example from bone marrow, can develop into only a few types of cell.

Advantages and disadvantages of using stem cells in medicine
Advantages	Disadvantages
Could treat conditions that are currently hard to treat, such as diabetes or paralysis.	Stem cells can divide out of control and form a tumour.
Could replace damaged cells with new healthy cells.	Viruses in donated stem cells could be passed to the patient and cause disease.
Could be used to grow replacement tissues.	The patient's immune system may reject cells from another person.
	Some people object to using embryos for ethical or religious reasons.

Exam tip:

In a 'discuss' question, include at least one advantage and one disadvantage, and finish by weighing them up.

Quick check

Put these in order, smallest first: organ, cell, organelle, tissue, organ system.
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Organelle, cell, tissue, organ, organ system.
What is the function of the mitochondria?
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They are where aerobic respiration takes place, releasing energy for the cell.
Name three structures found in plant cells but not animal cells.
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Cell wall, chloroplasts and a large permanent vacuole.
Biology only What is differentiation?
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The process by which a cell becomes specialised for a particular job.
Biology only Give one disadvantage of using stem cells in medicine.
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They can divide out of control and form a tumour (or viruses could be passed on, or the immune system may reject them).

Written and checked against the Edexcel IGCSE Biology (4BI1) specification · Updated October 2026

Frequently asked questions

Why do plant cells have a cell wall?

Plant cells have a cell wall to strengthen and support the cell. The wall is made of cellulose and lies outside the cell membrane. Animal cells do not have a cell wall. Together with the large vacuole of cell sap, which keeps the cell firm, the wall helps the plant hold its shape.

Why do plant cells have large vacuoles?

Plant cells have a large, permanent vacuole filled with cell sap, a solution of sugars and salts, which helps to keep the cell firm. Animal cells have no vacuole or only small, temporary ones. For Edexcel International GCSE Biology, learn the vacuole, cell wall and chloroplasts as the structures plant cells have but animal cells do not.

What is the difference between a tissue and an organ?

A tissue is a group of cells with a similar structure and function, while an organ is a group of different tissues working together to perform a specific function. The stomach is an organ because muscular tissue churns food, glandular tissue makes digestive juices and epithelial tissue covers its surfaces.

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