1
Triple only
[3 marks]In a required practical, a student grew seedlings in a box with a slit that let light in from one side only. After three days the shoots had bent towards the slit. Explain why.
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- auxin is unequally distributed / builds up on the shaded side of the shoot (1)
- cells on the shaded side grow (elongate) faster (1)
- so the shoot bends towards the light (1)
2
Triple onlyHigher tier
[3 marks]Give three ways in which plant hormones are used in agriculture, horticulture or the food industry.
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- auxins as weed killers / rooting powders / for tissue culture (1)
- ethene to control ripening of fruit during storage and transport (1)
- gibberellins to end seed dormancy / promote flowering / increase fruit size (1)
- allow any three different uses
- Max 3