9700_y16_sy
9700_y16_sy
9700_y16_sy
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Cambridge International AS and A Level Biology <strong>9700</strong> <strong>sy</strong>llabus Syllabus content<br />
15.2 Control and co-ordination in<br />
plants<br />
Plant co-ordination <strong>sy</strong>stems<br />
involve rapid responses as in<br />
the case of the Venus fly trap,<br />
but also complex interactions<br />
between plant growth<br />
regulators, such as auxin and<br />
gibberellin.<br />
Plants respond quite differently<br />
to different concentrations of<br />
plant growth regulators.<br />
a) describe the rapid response of the Venus fly trap to stimulation<br />
of hairs on the lobes of modified leaves and explain how the<br />
closure of the trap is achieved<br />
b) explain the role of auxin in elongation growth by stimulating<br />
proton pumping to acidify cell walls<br />
c) describe the role of gibberellin in the germination of wheat or<br />
barley<br />
d) explain the role of gibberellin in stem elongation including the<br />
role of the dominant allele, Le, that codes for a functioning<br />
enzyme in the gibberellin <strong>sy</strong>nthesis pathway, and the recessive<br />
allele, le, that codes for a non-functional enzyme<br />
38 www.cie.org.uk/alevel Back to contents page
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