CAIE A Level Biology 9700 · Cell membranes and transport
Root hair cells absorb nitrate ions from the soil. The concentration of nitrate ions in the soil solution is lower than that in the cytoplasm of the root hair cells. Explain the differences between active transport and facilitated diffusion, using the absorption of nitrate ions by root hair cells as an example.
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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