Community Q&A
A-Level Biology May/June 2025 Q5(b): Suggest and explain the advantages of using bone marrow stem cells from the blood sampl…
A-Level Biology · Paper 9700/22 · May/June 2025 · Question 5(b) · [3 marks]
Suggest and explain the advantages of using bone marrow stem cells from the blood sample to manufacture artificial red blood cells.
A full-marks model answer with a mark-by-mark examiner breakdown is below.
1 answer
- accepted ✓
-
Bone marrow stem cells can divide continuously by mitosis. This means a very large number of red blood cells can be produced from a small initial sample, creating a sustainable supply.
-
These are haematopoietic stem cells, which are already programmed to differentiate into various blood cells. This means they can be reliably stimulated to specialise into red blood cells.
-
Obtaining the stem cells from a blood sample is a significantly less invasive and safer procedure for the donor compared to the surgical extraction of bone marrow itself.
How the marks are awarded
- B1 — The answer states that the stem cells can divide continuously (by mitosis) and that this allows for the production of large numbers of red blood cells. This covers marking points 3 and 4.
- B1 — The answer correctly identifies that these are haematopoietic stem cells which are committed to the blood cell lineage and can differentiate into red blood cells. This covers marking point 1.
- B1 — The answer explains the advantage of using a blood sample is that it is a less invasive collection method for the donor compared to direct extraction from bone marrow. This covers marking point 6.
Common mistakes
- Confusing haematopoietic stem cells with embryonic stem cells and incorrectly stating they can differentiate into any cell type in the body.
- Giving a vague answer such as 'they can make more cells' without specifying continuous division by mitosis or the production of large quantities.
- Failing to address the part of the question about sourcing the cells 'from the blood sample', instead only giving general properties of stem cells.
- Stating that there would be no immune rejection, without qualifying that this would only be true if the cells were used for the original donor (an autologous transfusion).
Examiner tip: Always break down the question to identify all its components, ensuring your answer addresses each part, such as both the type of cell and its specific source.
AI-generated model answer, grounded in the official Cambridge mark scheme and reviewed by the MarkScheme team. Mark your own answer to this question →
-
Your answer
Sign in to answer this question.