Practise Stem cells. 12 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
What stem cells are, where they are found in embryos, adults and plants, and how they could be used in medicine and to clone plants. Expect recall questions and a longer 'evaluate' question weighing up benefits, risks and ethical issues.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
State what a stem cell isAn undifferentiated cell that can make more cells of the same type and can differentiate into other types of cell.
4
Name where stem cells are foundIn embryos, in adult bone marrow, and in the meristems of plants.
5
Compare embryonic and adult stem cellsEmbryonic stem cells can become most types of human cell; adult bone marrow stem cells form fewer types, including blood cells.
5
Describe uses of meristem cloningMaking clones quickly and cheaply, saving rare species, and producing crops with useful features.
6
Describe therapeutic cloning and its advantageAn embryo is made with the same genes as the patient, so its stem cells are not rejected.
7
Evaluate the use of stem cellsWeigh possible treatments against risks such as viral infection, and against ethical or religious objections, then give a conclusion.
Notes
What stem cells are
A stem cell is an undifferentiated cell. It can divide to make many more cells of the same type, and other types of cell can form from it by differentiation.
Embryonic stem cells (from human embryos) can be cloned and made to differentiate into most types of human cell.
Adult stem cells, e.g. from bone marrow, can form many types of cell, including blood cells, but fewer types than embryonic stem cells.
Meristem tissue in plants (at the tips of roots and shoots) can differentiate into any type of plant cell, throughout the life of the plant.
Uses in medicine
Treatment with stem cells may be able to help conditions such as diabetes (replacing insulin-producing cells) and paralysis (replacing damaged nerve cells).
In therapeutic cloning, an embryo is produced with the same genes as the patient. Stem cells from this embryo are not rejected by the patient's body, so they may be used for medical treatment. grade 6+
Adult stem cells from bone marrow are already used, e.g. in bone marrow transplants to treat some blood cancers.
Risks and issues
Stem cells grown in a laboratory could be infected with a virus, which would then be passed to the patient.
Some people have ethical or religious objections: embryos are destroyed to collect the stem cells, and some believe an embryo has a right to life.
Treatments are still being researched and may not work. Cells that keep dividing could also form a tumour.
Adult stem cells raise fewer objections (no embryo is destroyed) but can form fewer types of cell.
Plant meristems
Meristem cells can be used to produce clones of plants quickly and economically.
Rare species can be cloned to protect them from extinction.
Crop plants with special features, such as disease resistance, can be cloned to produce large numbers of identical plants for farmers.
Because the clones are genetically identical, a new disease that affects one plant could affect them all. grade 7+
Cheatsheet
Stem cell: an undifferentiated cell that can make more cells of the same type and can differentiate into other types
Embryonic stem cells: can form most types of human cell
Adult bone marrow stem cells: form many types of cell, including blood cells
Meristems (root and shoot tips): can form any type of plant cell, throughout the plant's life
Therapeutic cloning: embryo with the patient's genes, so the stem cells are not rejected grade 6+
Possible treatments: diabetes, paralysis
Risks and issues: viral infection; ethical and religious objections
Meristem cloning: fast and cheap; protects rare species; copies crops with useful features
How to answer each type of question
Compare stem cells from different sources
1 to 2 marks4
State which cells each type of stem cell can form.
Write it as a comparison, using 'but' or 'whereas'.
Example. Give one difference between stem cells from a human embryo and stem cells from adult bone marrow.
Show the model answer
Embryonic stem cells can differentiate into most types of human cell, whereas adult bone marrow stem cells can form fewer types, such as blood cells (1).
Give reasons for cloning plants from meristems
2 to 3 marks5
Speed and cost: clones are produced quickly and economically.
Conservation: rare species can be saved from extinction.
Crops: every clone has the same useful feature, e.g. disease resistance.
Example. Give two reasons why plant growers use meristem tissue to clone plants.
Show the model answer
Any two from: large numbers of plants can be produced quickly (1) it is cheap / economical (1) all the plants have the same desired features, e.g. disease resistance (1) rare species can be protected from extinction (1)
Explain why cells from therapeutic cloning are not rejected
2 marks6
Say that the embryo, and so the stem cells, have the same genes as the patient.
Say that the patient's body therefore does not reject the cells.
Example. Explain why stem cells produced by therapeutic cloning would not be rejected by the patient.
Show the model answer
The embryo / stem cells have the same genes as the patient (1), so the patient's immune system does not recognise the cells as foreign and does not reject them (1).
6-mark: evaluate the use of stem cells
6 marks (level of response)7
Give the benefits: possible treatments, better quality of life, no rejection with therapeutic cloning.
Give the risks: viral infection, treatment may not work, possible tumours.
Give the ethical and religious issues: embryos are destroyed.
Finish with a conclusion that weighs up both sides and gives a reason.
Example. Scientists hope to use embryonic stem cells to treat people who are paralysed after a spinal injury. Evaluate the use of embryonic stem cells to treat paralysis.
Show the model answer
Model answer: Embryonic stem cells can differentiate into most types of human cell, including nerve cells, so they could replace the damaged nerve cells and give patients back some movement and a better quality of life. If therapeutic cloning is used, the embryo has the same genes as the patient, so the new cells would not be rejected. However, the treatment is still being researched and may not work. Stem cells grown in a laboratory could be infected with a virus that would be passed to the patient, and cells that keep dividing could form a tumour. Many people have ethical or religious objections, because embryos are destroyed to collect the stem cells and some believe an embryo has a right to life. Adult stem cells avoid this problem but cannot form as many types of cell. Overall, the treatment could greatly improve patients' lives, but it should only be used once trials show that it is safe and works. Level 3 (5 to 6 marks): benefits, risks and ethical issues all described, with a conclusion supported by a reason. Level 2 (3 to 4 marks): at least one benefit and one risk or ethical issue described, with little or no conclusion. Level 1 (1 to 2 marks): one or two simple relevant points.
Shortcuts and memory tricks
Three sources of stem cells: Embryos, Adult bone marrow, Meristems ('EAM').
Stem cell uses in medicine: think 'D and P': Diabetes and Paralysis.
Evaluate = both sides + a conclusion. No conclusion, no top level.
Where marks are lost
Saying adult stem cells can become any type of cell. Bone marrow stem cells form only some types, such as blood cells.
Saying stem cells are 'specialised'. They are undifferentiated.
Saying therapeutic cloning produces a baby. It produces an embryo as a source of stem cells.
Writing a one-sided answer to an 'evaluate' question, with no risks or no conclusion.
Giving vague ethical points, such as 'it is wrong'. Say why: embryos are destroyed, and some believe an embryo has a right to life.
Exam technique
In 6-mark 'evaluate' questions, plan quickly: benefits, risks, ethics, conclusion.
Use the words 'undifferentiated' and 'differentiate' when you describe stem cells.
If the question is about plants, write about meristems and cloning, not embryos.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Stem cells are found in animals and plants. Name the tissue in plants that contains stem cells.
meristem
Therapeutic cloning can be used to produce stem cells for a patient. The steps are listed below, but they are not in the correct order.
A Stem cells are removed from the embryo.
B The nucleus is removed from an egg cell from a donor.
C The egg cell divides to form an embryo.
D The nucleus from one of the patient's body cells is put into the egg cell.
E The stem cells are made to differentiate into the type of cell the patient needs.
Write the letters A to E in the correct order.
B, D, C, A, E
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Stem cells are found in animals and plants.
(a) Which statement describes a stem cell? Tick (✓) one box.[1]
A cell that has no nucleus
A specialised cell that can no longer divide
An undifferentiated cell that can give rise to many more cells of the same type
A cell that is found only in plant stems
(b) Name the tissue in plants that contains stem cells.[1]
(c) Name one type of cell that stem cells from adult bone marrow can form.[1]
(d) Give one medical condition that treatment with stem cells may be able to help.[1]
Show the answer and mark scheme
(a)Answer: An undifferentiated cell that can give rise to many more cells of the same type
(b)Answer: meristem
meristem (tissue)
(c)
blood cells / red blood cells / white blood cells / platelets
(d)
diabetes / paralysis
Question 2Medium5 marks
Stem cells can be taken from human embryos or from adult bone marrow.
(a) Give one difference between stem cells from embryos and stem cells from adult bone marrow.[1]
(b) Describe how therapeutic cloning is used to produce stem cells for a patient. Explain why these stem cells are useful for medical treatment.[3]
(c) Give one risk of using stem cells in medical treatment.[1]
Show the answer and mark scheme
(a)
embryonic stem cells can differentiate into most types of human cell, but adult bone marrow stem cells can form only some types, e.g. blood cells
(b)
an embryo is produced with the same genes as the patient
stem cells are taken from the embryo (and made to differentiate into the cells needed)
the cells are not rejected by the patient's body / immune system
(c)
transfer of a viral infection (to the patient)
Question 3Hard9 marks
A patient has paralysis caused by a damaged spinal cord. Doctors are considering two treatments:
Treatment 1 – stem cells taken from an embryo produced by therapeutic cloning
Treatment 2 – stem cells taken from the patient's own bone marrow.
(a) Evaluate the two treatments. You should give a conclusion.[6]
(b) Scientists grew 2 × 104 embryonic stem cells in a culture. The number of cells doubled every 36 hours. Calculate the number of cells after 9 days. Give your answer in standard form.[3]
Show the answer and mark scheme
(a)
treatment 1: embryonic stem cells can differentiate into most types of cell, including nerve cells
treatment 1: the embryo has the same genes as the patient, so the cells are not rejected
treatment 1: the embryo is destroyed, so some people have ethical or religious objections
treatment 2: the cells are the patient's own, so they are not rejected
treatment 2: fewer ethical objections as no embryo is destroyed / the patient can give consent
treatment 2: bone marrow stem cells can form only some types of cell (e.g. blood cells), so may not form nerve cells
both: risk of transferring a viral infection; treatments are new / not fully tested
conclusion with a reason, e.g. treatment 1 is more likely to repair the spinal cord because the cells can form nerve cells
Marked with levels of response: the full level descriptors are in the app.