Explain why maintaining a stable blood glucose concentration is important for cells in the body.

Cambridge International IGCSE Biology (0610) — 14.3 Hormones · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

If blood glucose concentration is too high, the water potential of the blood decreases, so water moves out of cells into the blood by osmosis, causing cells to shrink or die. If blood glucose concentration is too low, the water potential of the blood increases, so water moves into cells by osmosis, causing them to burst or lyse. Maintaining a stable blood glucose concentration therefore provides a reliable, constant energy source for cells and prevents osmotic damage.

Examiner tips

Use the word ‘osmosis’ and explain the direction of water movement.
Show the two harmful outcomes (cell shrinkage and cell lysis).
Mention the energy‑supply benefit to complete the answer.
Keep the answer concise and use the exact terminology from the mark scheme.

Common mistakes

Confusing high glucose with high water potential; students say ‘high water potential’ instead of ‘low’.
Failing to mention both cell shrinkage and cell bursting, or only one of them.
Using vague terms like ‘damage’ instead of ‘shrink’ or ‘burst’.

Mark scheme (4 marks)

If blood glucose concentration is too high, the water potential of the blood decreases / becomes very low
Water moves out of cells into the blood by osmosis, causing cells to shrink / die
If blood glucose concentration is too low, the water potential of the blood increases / is higher than that of cells
Water moves into cells by osmosis, causing them to burst / lyse; OR stable blood glucose provides a reliable / constant energy source for cells

Key terms in this question

blood glucose concentration