What are stem cells and where are they found? Revision Notes | GCSE AQA Higher Biology
A stem cell is an undifferentiated cell, one that hasn't specialised yet. Free GCSE AQA Biology notes with key terms and 15 questions answered.
Updated 20 Mar 2026 · Revise Right Team
What are stem cells and where are they found? is part of Cell division in GCSE AQA Higher Biology.
4 min
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What this lesson covers
A stem cell is an undifferentiated cell, one that hasn't specialised yet. Free GCSE AQA Biology notes with key terms and 15 questions answered.
Define what stem cells are and explain their key characteristic of being undifferentiated
Describe the function of stem cells in embryos, adult animals, and plant meristems
Compare embryonic stem cells, adult stem cells, and plant meristem cells in terms of what they can become
Explain why stem cells are important for growth, repair, and development in living organisms
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Use this lesson to stay inside Cell division while connecting the detail back to the wider Cell biology topic.
Cell biology
Cell division
GCSE AQA Higher Biology
Revision notes
Read the core explanations from What are stem cells and where are they found? before testing yourself from memory.
1. What Makes a Cell 'Stem'?
Picture a factory that hasn't decided what to make yet. It has all the machinery and potential, but it's waiting for instructions. That's essentially what a stem cell is — a biological factory with unlimited potential.
The key word here is 'undifferentiated'. Think of it like this: a stem cell is like a blank template that hasn't been given a specific job yet. It can become a muscle cell, a nerve cell, a blood cell — whatever the body needs.
Trap: Many students think stem cells are 'baby cells' that grow into adult cells. Actually, stem cells are cells that haven't specialised yet — they could be found in a fully grown adult.
2. Embryonic Stem Cells - The Ultimate Potential
In the early stages of development, an embryo is essentially a ball of stem cells. These embryonic stem cells are the most versatile — they're like a master key that can unlock any door.
Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells. This means they could potentially become brain cells, heart cells, liver cells, skin cells — almost anything the body needs.
Think of embryonic development like building a house. You start with basic materials (stem cells) that can be shaped into walls, windows, doors, or roof tiles depending on where they're needed in the structure.
3. Adult Stem Cells - The Repair Crew
Even after you're fully grown, your body keeps a reserve of stem cells for repairs and maintenance. These adult stem cells are more limited than embryonic ones — they're like specialist tools rather than the master key.
The most well-known example is bone marrow. Stem cells from adult bone marrow can form many types of cells including blood cells. Every day, your bone marrow produces millions of new red blood cells, white blood cells, and platelets to replace the ones that wear out.
Other adult stem cells exist in your skin (replacing dead skin cells), your gut lining (replacing cells damaged by stomach acid), and even in your brain (though these are much more limited).
4. Plant Stem Cells - Growing for Life
Plants have a clever advantage over animals — they keep their stem cells active throughout their entire lives. These stem cells are found in regions called meristems.
Meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant. This is why a tree can keep growing new branches, leaves, and roots for hundreds of years — it never runs out of stem cells.
You'll find meristems at root tips (for growing downwards), shoot tips (for growing upwards), and in the cambium layer (for growing outwards, making the trunk thicker).
5. Comparing the Three Types
Now let's see how these three types of stem cells stack up against each other. Each has different capabilities and limitations.
Worked example: Comparing Stem Cell Types
Compare embryonic stem cells, adult stem cells, and plant meristem cells in terms of what they can become.
Can differentiate into most different types of human cells — Can differentiate into most different types of human cells
Can form many types of cells but more limited than embryonic — Example: bone marrow → blood cells, but not brain cells
Can differentiate into any type of plant cell — Can differentiate into any type of plant cell
Plant meristems remain active throughout life — Unlike animals, plants never 'finish' developing
Answer: Embryonic stem cells can become most types of human cell, adult stem cells are more limited, and plant meristems can produce any type of plant cell throughout the plant's life.
6. Exam Technique - Getting Full Marks
Stem cell questions often test your ability to describe functions and compare different types. Here's how to nail the marks every time.
Command word focus: 'Describe' questions want you to state what happens. 'Explain' questions want you to say why it happens. For stem cells, describing is about what they can become; explaining is about why this ability is useful for the organism.
Common mistake: Don't confuse stem cells with gametes (sex cells). Stem cells can become different body cells; gametes are for reproduction. They're completely different things with different jobs.
Sources and content standards
Published by Revise Right. Use the official specification reference to check the requirements for your course. Content updated: 2026-03-20.
A stem cell is an undifferentiated cell, one that hasn't specialised yet. Like a blank template that hasn't been given a specific job, a stem cell can become a muscle cell, a nerve cell, a blood cell or whatever the body needs.
Where are stem cells found?
Stem cells are found in embryos, in adult animals and in plants. Adult stem cells exist in places such as bone marrow, skin and the gut lining, while plant stem cells are found in meristems at root tips, shoot tips and the cambium layer.
What is a meristem?
A meristem is a region of a plant where stem cells are found. Meristem tissue can differentiate into any type of plant cell, throughout the life of the plant, and meristems are found at root tips, shoot tips and in the cambium layer.
What do you need to know about stem cells for GCSE biology?
Stem cells are undifferentiated cells that can give rise to many more cells of the same type and differentiate into other cells. They are found in embryos, which can become most types of human cell, adult bone marrow, which can form blood cells, and plant meristems, which can form any plant cell.
What can bone marrow stem cells become?
Stem cells from adult bone marrow can form many types of cells, including blood cells. Every day, bone marrow produces millions of new red blood cells, white blood cells and platelets to replace the ones that wear out, but these adult stem cells cannot form brain cells.
What does undifferentiated mean?
Undifferentiated means a cell has not specialised yet and has not been given a specific job. A stem cell is undifferentiated, like a blank template, so it can become a muscle cell, a nerve cell or a blood cell, whatever the body needs.
What can embryonic stem cells become?
Embryonic stem cells can be cloned and made to differentiate into most different types of human cells, such as brain, heart, liver and skin cells. In the early stages of development, an embryo is essentially a ball of these versatile stem cells.
What is the cambium in plants?
The cambium is a layer of meristem tissue in plants used for growing outwards, making the trunk thicker. Other meristems are found at root tips, for growing downwards, and shoot tips, for growing upwards.
Why can trees keep growing for hundreds of years?
Trees can keep growing for hundreds of years because plants keep their stem cells active throughout their entire lives in meristems. Meristem tissue can differentiate into any type of plant cell, so a tree never runs out of stem cells for new branches, leaves and roots.
Where are adult stem cells found in the body?
Adult stem cells are found in bone marrow, which forms blood cells, the skin, which replaces dead skin cells, the gut lining, which replaces cells damaged by stomach acid, and even the brain, though these are much more limited.
Are stem cells baby cells?
Stem cells are not 'baby cells' that grow into adult cells. They are cells that have not specialised yet, and they can be found in a fully grown adult, for example in bone marrow.
What is the difference between stem cells and gametes?
Stem cells and gametes are completely different things with different jobs. Stem cells can become different body cells, while gametes (sex cells) are for reproduction.
Compare embryonic stem cells, adult stem cells and meristem cells.
Embryonic stem cells can become most types of human cell, adult stem cells can form many types of cells but are more limited, such as bone marrow forming blood cells, and plant meristem cells can produce any type of plant cell throughout the plant's life.
What is the difference between embryonic and adult stem cells?
Embryonic stem cells can be made to differentiate into most different types of human cells, while adult stem cells are more limited. For example, stem cells from adult bone marrow can form many types of cells including blood cells.
Why are stem cells important?
Stem cells are important for growth, repair and development. Adult stem cells act as a repair crew: every day, bone marrow produces millions of new red blood cells, white blood cells and platelets to replace the ones that wear out.