CAIE A Level Biology 9700 · Cell membranes and transport
A researcher compares the cell surface membranes of human red blood cells and liver cells. Both cells have glycoproteins in their membranes, but the immune system can distinguish between them. Using the fluid mosaic model, explain how the structure of glycoproteins allows cells to be recognised by other cells.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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