Describe stem cells in tissue repair
Stem cells divide by mitosis and can differentiate into specialised cells, supplying replacements for cells lost or damaged in tissues.
AS Level · Cambridge International Biology 9700, 2028–2030. These lessons explain cell-cycle concepts and image interpretation. Written practice is self-checked; it does not demonstrate practical microscopy competence or replace teacher-reviewed assessment.
Before you begin
- Recognise DNA as genetic material and use the terms cell, nucleus and chromosome accurately.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
How can mitosis by a stem cell help maintain a tissue?
What you will learn
- Outline how mitosis by stem cells supplies cells for replacement and tissue repair
- Relate stem-cell division to differentiation into specialised cells
Stem cells provide a source of new cells
Stem cells can divide by mitosis to produce additional cells. Some daughter cells remain stem cells, while others can differentiate into specialised cell types. This allows a tissue to maintain a supply of cells for replacement.
In tissue repair, replacement cells can fill gaps left by damaged or dead cells. Mitosis supplies new cells; differentiation gives cells the structures and functions needed for a particular tissue.
Keep the role and limitation clear
Different tissues have different stem-cell populations and capacities. A statement about stem cells should name the tissue context when one is supplied and avoid assuming that any stem cell can produce every cell type.
This syllabus outcome focuses on the role of stem cells in cell replacement and tissue repair by mitosis. It does not require a clinical claim that stem-cell treatment will repair a particular disease.
Pause and explain
What does differentiation mean in this context?
Worked example
A tissue contains stem cells and has lost some specialised cells after damage. Outline how stem cells can help restore the tissue.
Show the worked solution
- Stem cells divide by mitosis.
- Some daughter cells can differentiate into cells of the tissue.
Answer Stem cells divide by mitosis to supply new cells. Some daughter cells can differentiate into the specialised cells needed to replace cells lost or damaged in the tissue.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Outline the role of stem cells in tissue repair.
Give me a hint
Include mitosis and the fate of some daughter cells.
Compare my reasoning
- Stem cells divide by mitosis to make additional cells.
- Some daughter cells differentiate and replace damaged or dead cells.
Stem cells divide by mitosis to supply new cells. Some daughter cells differentiate into specialised cells that replace damaged or dead cells and help repair the tissue.
Look for these in your work
- Mitosis included
- Differentiation and replacement linked
Distinguish cell division from differentiation in a stem-cell pathway.
Give me a hint
State what increases in number and what changes in cell function.
Compare my reasoning
- Mitosis produces additional daughter cells.
- Differentiation gives a cell specialised structures and functions.
Mitosis increases cell number by producing daughter cells. Differentiation is the development of specialised structures and functions in some of those cells.
Look for these in your work
- Mitosis defined
- Differentiation defined
A student claims a stem cell can always replace any damaged cell in any organ. Improve the claim.
Give me a hint
Use a tissue-specific, appropriately limited explanation.
Compare my reasoning
- Stem-cell capacity depends on the cell population and tissue.
- Some stem cells provide replacement cells that can differentiate into particular specialised cells.
Stem-cell capacity depends on the cell population and tissue. Some stem cells divide by mitosis and can provide daughter cells that differentiate into particular specialised cells for replacement or repair; this does not mean every stem cell can replace every cell type.
Look for these in your work
- Scope qualified
- Mechanism stated
Common mistakes
- Claiming every stem cell can form every possible cell type
- Confusing mitosis with differentiation
- Promising a medical outcome from a general biological mechanism
What can you explain now?
How can mitosis by a stem cell help maintain a tissue?
Compare with the explanation
It supplies new cells for replacement
Mitosis increases the number of cells available.
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Make it stick
How can stem-cell mitosis and differentiation work together in cell replacement and tissue repair?
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