Stem cells: compare potential, matching and ethical choices
הוצג| English | משמעות |
|---|---|
| stem cell/stem sel/ | תא גזעי |
| meristem/ˈmerɪstəm/ | מריסטמה |
| therapeutic cloning/ˌθerəˈpjuːtɪk ˈkləʊnɪŋ/ | העתקה טיפולית |
What would explain this observation?
- A cell that can divide and specialize may help replace damaged tissue. The possible benefit depends on which cell types it can produce and on evidence about risks.
Build the model
- A stem cell 干细胞 is undifferentiated and can produce more stem cells and some differentiated cells.
- Human embryonic stem cells can differentiate into most human cell types.
- Adult bone-marrow stem cells can form several cell types, including blood cells.
- Plant meristems 分生组织 can form any plant cell type throughout life.
- stem cell: An undifferentiated cell able to divide and give rise to some specialized cells.
- meristem: Plant tissue containing cells that can continue dividing and differentiating.
- therapeutic cloning 治疗性克隆: Production of an embryo genetically matching a patient for potential stem-cell treatment.
Which comparison matches the stated GCSE model?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
In the GCSE model, embryonic stem cells can form many cell types while bone-marrow stem cells form a limited range, mainly blood cells. Adult differentiated cells are not stem cells, and meristems are plant tissues.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Therapeutic cloning produces an embryo with the patient’s genes, so its stem cells offer a genetic match and reduced rejection in the specification’s model.
- Potential applications include conditions such as diabetes or paralysis.
- These are potential benefits, not guaranteed cures.
- Viral transfer and ethical or religious objections must be considered with the evidence.
In the lab: Evaluate a supplied fictional research proposal using benefit, evidence, risk and value judgement as separate headings. AQA does not require laboratory stem-cell techniques. For plants, compare rapid economical production of genetically identical disease-resistant crops with conserving rare plants and retaining genetic diversity.
Which two habits make the investigation or model in this case more defensible?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- Known: an approved model nursery starts with five identical plant clones and each produces four new clones.
- New clones = 5×4=20.
- If the originals remain, total plants =25.
- The number increases, but cloning alone does not add genetic variety; a shared susceptibility could affect the whole group.
Your turn: Six retained model parent plants each produce three new clones. Find the total including parents.
Six retained model parent plants each produce three new clones. Find the total including parents.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 24 plants. Known: 6 parent plants each produce 3 new clones. New clones = 6 x 3 = 18. Total including the retained parents = 18 + 6 = 24 plants.
Check the conclusion and its limits
- Adult bone-marrow stem cells are not assumed to form every body cell type.
- Genetic matching does not remove every medical risk.
- Cloning a rare species can increase its number, while habitat protection and genetic diversity still require attention.
Not true: A genetically matched stem-cell treatment is guaranteed to have no risks. Genetic matching reduces rejection risk but cannot remove every risk - infection, procedure complications and unexpected behaviour remain. No medical treatment is risk-free.
- A stem cell is undifferentiated and can produce more stem cells and some differentiated cells.
- Therapeutic cloning produces an embryo with the patient’s genes, so its stem cells offer a genetic match and reduced rejection in the specification’s model.
- Watch for: adult bone-marrow stem cells are not assumed to form every body cell type.
Genetic matching reduces rejection risk but cannot remove every risk - infection, procedure complications and unexpected behaviour remain.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
True. Genetic matching reduces rejection risk but cannot remove every risk - infection, procedure complications and unexpected behaviour remain. No medical treatment is risk-free.
An undifferentiated cell able to divide and give rise to some specialized cells: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
stem cell means An undifferentiated cell able to divide and give rise to some specialized cells.