1.12 Stem cells
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Which type of cell can differentiate into any type of body cell?
Choose one answer.
Correct Not quite: the answer is An embryonic stem cell
Mark scheme
B (An embryonic stem cell)
Model answer
B: An embryonic stem cell. Embryonic stem cells can become any type of cell. Adult stem cells can only become some types.
Where are stem cells found in a plant, and what can they become?
Mark scheme
- in meristems / at the tips of roots and shoots (1)
- any type of plant cell (1)
Model answer
Stem cells are found in the meristems at the tips of the roots and shoots. They can become any type of plant cell.
Give two ways in which stem cells could be used to treat people.
Mark scheme
Any two from:
- to treat paralysis / replace damaged nerve cells (1)
- to treat diabetes / make insulin-producing cells (1)
- to treat blood diseases / bone marrow transplants (1)
- to replace any damaged or lost tissue (1)
Model answer
Stem cells could be used to replace damaged nerve cells in paralysis, and to make cells that produce insulin to treat diabetes.
Stem cells from a therapeutic clone of a patient are not rejected by the patient's body.
Explain why.
Mark scheme
- the embryo has the same genes as the patient (1)
- so the cells are not recognised as foreign / the patient's immune system does not attack them (1)
Model answer
The cloned embryo has the same genes as the patient, so the patient's immune system does not recognise the stem cells as foreign and does not attack them.
Give one risk, one ethical objection and one benefit of using embryonic stem cells in medicine.
Mark scheme
- risk, for example: a virus could be passed on to the patient / the cells could form a tumour (1)
- objection, for example: embryos are destroyed / some people believe an embryo has a right to life / religious objections (1)
- benefit, for example: could treat diseases that are not curable now / can become any type of cell (1)
Model answer
A risk is that a virus in the stem cells could be passed to the patient. An objection is that embryos are destroyed to get the cells. A benefit is that they could be used to treat diseases that cannot be cured now.
Explain how cells from the meristem of a rare plant could be used to stop the plant becoming extinct.
Mark scheme
- meristem cells can be grown / cloned into new plants (1)
- many identical plants can be made quickly (1)
Model answer
Meristem cells can be grown into complete new plants, so many identical copies of the rare plant can be produced quickly and planted out.
Compare embryonic stem cells with adult stem cells.
Mark scheme
Any four from:
- embryonic stem cells come from an embryo; adult stem cells come from adult tissue such as bone marrow (1)
- embryonic stem cells can become any type of cell (1)
- adult stem cells can only become some / a limited number of types of cell (1)
- getting embryonic stem cells destroys an embryo, which some people object to (1)
- getting adult stem cells does not destroy an embryo, so there are fewer ethical objections (1)
Model answer
Embryonic stem cells come from an early embryo and can become any type of body cell. Adult stem cells come from tissues such as bone marrow and can only become some types of cell, for example blood cells. Using embryonic stem cells destroys an embryo, which some people object to, but using adult stem cells does not.
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