1
Triple only
[1 mark]Which describes the response of a root to gravity?
- Positive phototropism
- Negative gravitropism
- Positive gravitropism
- Negative phototropism
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Answer: C C
2
Triple only
[3 marks]A shoot is lit from one side. Explain how auxin makes the shoot bend towards the light. (3)
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- auxin moves to the shaded side (1)
- auxin makes the cells on the shaded side elongate / grow faster (1)
- so the shoot bends towards the light (1)
3
Triple only
[2 marks]A seedling root is placed on its side. Describe how the root responds to gravity. (2)
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- root grows downwards / bends towards gravity (1)
- auxin collects on the lower side and slows the growth of cells there (1)
4
Triple onlyHigher tier
[3 marks]Give one commercial use of each of the following plant hormones. (a) Auxins (1) (b) Gibberellins (1) (c) Ethene (1)
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- auxins: weedkiller / rooting powder (1)
- gibberellins: any one of germination of seeds / fruit and flower formation / production of seedless fruit (1)
- ethene: ripening of fruit (1)
5
Triple onlyHigher tier
[2 marks]Bananas are picked while green and transported in cool containers. Explain why growers expose them to ethene before they are sold. (2)
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- ethene makes the fruit ripen (1)
- so all the fruit is ripe at the same time / ripens when it is needed in the shops (1) allow so it does not spoil during transport