A farmer sprays a wheat field with a weedkiller that contains auxin.
The broad-leaved weeds die but the wheat does not.
Which statement explains this?
The weeds absorb more of the auxin, so the growth of the weeds stops completely
The wheat absorbs more of the auxin, so the wheat grows faster than the weeds
The weeds absorb more of the auxin, so the weeds grow too fast and then die
The weeds absorb less of the auxin, so the weeds cannot grow towards the light
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59 exam-style questions on AQA GCSE Biology 5.4 Plant hormones, covering 5.4.1 Control and coordination and 5.4.2 Use of plant hormones (HT only). Each one has a worked solution and a mark scheme showing where the marks go.