Tropism, the roles of auxin and plant hormones in agriculture

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  • Created by: Louise98
  • Created on: 11-04-14 12:55
What is a tropism?
"directional growth responce" Plants grow in a certain direction in response to a stimulus.
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What is Auxin?
Auxin is a plant hormone that controls growth near the tips of the shoots and roots. In the shoots auxins make the cells grow QUICKER. And in the roots auxins make the cells grow SLOWER.
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Where is Auxin produced?
Auxin is produced in the tips and moves backwards to stimulate cell elongation which occurs in the cells just behind the tips.
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What happens if the tip of a shoot is removed?
If the tip of the shoot is removed no auxin is available so the shoot may stop
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What does Extra Auxin do?
Extra auxin promotes growth in the shoot but inhibits growth in the root to produce the desired result.
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What is the stimulus and response to Phototropism?
the stimulus is light. The shoots go towards the light so it is a positive phototopism and the roots go away from the light so it is a negative phototropism.
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What is the stimulus and response to Geotropism/Gravitropism?
The stimulus is gravity. Shoots go away so it is a negative gravitropism and the roots go towards so it is a positive gravitropism.
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What is the stimulus and response to Hydrotropism?
The stimulus is water. Shoots go away from the water so it is a negative hydrotropism and the roots go towards the water so it is a postive hydrotropism.
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What happens when the shoots grow towards light?
When a shoot tip is exposed to light more auxin accumuates on the side that is in the shade than the side that is in the light. This makes the cell grow faster on the shaded side so the shoot bends towards the light.
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What happens when the shoots grow away from gravity?
When a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip with more auxin on the lower side. This causes the lower side to grow faster, bending the shoots upwards.
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What happens when the roots grow towards gravity?
a root growing sideways will have mroe auxin on its lower side. But in a root the extra auxin inhibits growth. This means the cells on top elongate faster and the root bends downwards.
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What happens when the roots grow towards moisture?
An uneven amount of moisture either side of a root produces more auxin on the side with more moisture. This inhibits growth on that side, causing the root to bend in that direction towards the moisture.
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What are selective weedkillers?
Selective weedkillers kill some plants but not others. It has growth hormones making the weeds grow too quickly and kills them.
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Why do gardeners use rooting powders?
Gardeners use rooting powder which has auxin hormones in so then it will cause the roots to grow.
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What is the advantage of using plant hormones to ripen fruit?
By using plant hormones to ripen fruit it makes them ripen alot quicker than normal making it quicker to sell.
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What is dormancy?
when the seeds stop germinating until conditions are right.
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Card 2

Front

What is Auxin?

Back

Auxin is a plant hormone that controls growth near the tips of the shoots and roots. In the shoots auxins make the cells grow QUICKER. And in the roots auxins make the cells grow SLOWER.

Card 3

Front

Where is Auxin produced?

Back

Preview of the front of card 3

Card 4

Front

What happens if the tip of a shoot is removed?

Back

Preview of the front of card 4

Card 5

Front

What does Extra Auxin do?

Back

Preview of the front of card 5
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