Stem Cells
Practise Stem Cells for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Be ready to discuss the benefits and ethical issues of embryonic stem cells, and how therapeutic cloning avoids the problem of rejection.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
A stem cell is an undifferentiated cell that can divide to produce more cells of the same type, and can differentiate into other cell types.
Embryonic stem cells can differentiate into any type of cell, which makes them extremely versatile. Adult stem cells, found in tissues such as bone marrow, can form only a limited range — for example blood cells. Plant meristem tissue contains stem cells that can differentiate throughout the plant's life.
Stem cells have real medical potential, including treating conditions such as diabetes and paralysis. They also raise ethical objections, and exam questions often ask you to discuss both sides rather than simply describe the science.
Revision notes
Types of stem cell
Embryonic stem cells come from early embryos and can differentiate into any cell type.
Adult stem cells, from tissue such as bone marrow, differentiate into a limited range only. Plant meristems contain stem cells able to differentiate throughout the plant's life.
Therapeutic cloning
In therapeutic cloning, an embryo is produced with the same genes as the patient.
Stem cells from that embryo are not rejected by the patient's immune system, so they may be used to treat their condition. This is a key advantage worth stating.
Benefits and objections
Benefits: stem cells could treat conditions such as diabetes and paralysis, and could relieve suffering.
Objections: some people object on ethical or religious grounds because an embryo is destroyed. There are also practical risks such as viral infection during transfer.
Key points
- A stem cell is undifferentiated and can become other cell types.
- Embryonic stem cells can form any cell type.
- Adult stem cells form a limited range only.
- Plant meristems contain stem cells throughout life.
- Therapeutic cloning avoids immune rejection.
- Ethical objections exist because embryos are destroyed.
Worked examples
Example 1
Define a stem cell. [2 marks]
Model answer
A stem cell is an undifferentiated cell (1 mark) that can divide to produce more cells of the same type and differentiate into other cell types (1 mark).
Example 2
Give one advantage of using stem cells from therapeutic cloning to treat a patient. [2 marks]
Model answer
The embryo produced has the same genes as the patient (1 mark), so the stem cells are not rejected by the patient's immune system (1 mark).
Example 3
Give one benefit and one objection to the use of embryonic stem cells in medicine. [2 marks]
Model answer
Benefit: they could be used to treat conditions such as diabetes or paralysis and relieve suffering (1 mark). Objection: some people object on ethical or religious grounds because an embryo is destroyed in the process (1 mark).
Common mistakes
Saying adult stem cells can become any cell type.
Only embryonic stem cells can. Adult stem cells form a limited range.
Giving only one side in a discussion question.
Questions on stem cells usually require both a benefit and an objection.
Confusing therapeutic with reproductive cloning.
Therapeutic cloning produces cells for treatment, not a whole organism.
Forgetting the immune rejection point.
It is the main scientific advantage of therapeutic cloning and is often worth a mark.
Exam tips
- Use the word undifferentiated in your definition.
- Give both a benefit and an objection when a question asks you to evaluate.
- Mention immune rejection when discussing therapeutic cloning.
- Distinguish embryonic, adult and plant meristem stem cells.
Key terms
- Stem cell
- An undifferentiated cell able to differentiate into other cell types.
- Meristem
- Plant tissue containing stem cells, found at growing tips.
- Therapeutic cloning
- Producing an embryo with the same genes as a patient to obtain stem cells.
- Undifferentiated
- Not yet specialised for a particular function.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.