CAIE A Level Biology 9700 · Control and coordination
A student investigated the effect of auxin on cell elongation in coleoptile segments. Segments of equal initial length were placed in a solution containing auxin or in a control solution without auxin. After 24 hours, the mean cell length was measured.
| Treatment | Mean cell length / μm |
|---|---|
| Auxin | 200 |
| Control | 120 |
Outline the mechanism by which auxin stimulates cell elongation. Use data from the table to support your answer.
7 marks, so the mark scheme is looking for about 7 separate creditworthy points. Making the same point twice in different words earns it once.
Outline means: Give the main points briefly. Less detail than describe, but every key step has to be there. One short line per step, in order. The marks are for coverage, not depth.
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