Controlling plant growth

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  • Created by: Esme.B
  • Created on: 30-10-17 11:47
What is Apical Dominance?
Stem will grow upwards rather than outwards.
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where's Auxin produced?
The apical meristem
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What is auxin hormone responsible for?
responsible for regulating plant growth
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What is the gibberellins hormone responsible for?
responsible for the control of stem elongation + seed germination
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List 4 points relating to the mechanism for apical dominance.
1. Auxin made by cells in the shoot tip. 2. Auxin transported downwards cell to cell. 3. Auxin accumulates in the nodes beside the lateral buds. 5. Presence inhibits their activity
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what occurs when the tip of the shoot is cut off, one is treated and the other is untreated?
IAA (indole-3-acetic-acid) is applied to one + it continues to show apical dominance. 2. The untreated shoot will branch sideways
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What 2 aspects occurs when a growing shoot is tipped upside down?
1. Apical dominance is prevented. 2.Latral buds start to grow out sideways.- supports the theory that auxins are transported downwards, and can not be transported upwards against gravity.
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What evidence is present which is against 'mechanism'?
Abscisic acid- inhibits bud growth: High auxin may keep abscisic acid lev els high (i.e-Synergy)+Cytokinins-promote bud growth:High auxin makes shoot apex a sink for cytokinins/when tip is removed cytokinin spreads more evenly around plant promoti
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What other two hormones affect the auxin levels + growth inhibition?
Abscisic Acid:inhibits bud growth + cytokinnins= promotes bud growth
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How does Abscisic acid have a direct effect on the growth of the plant?
High auxin levels in shoot=keep high Abscisic acid levels high in bud. Tip(apex) removed=Abscisic acid levels drops+buds starts to grow
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How does Cytokinins have a direct effect on the growth of the plant?
Directly applying cytokinins bud=overrides apical dominance effect. High levels of Auxins= mades shoot apex a sink for cytokinins to be produced in the roots.
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Where does most of the Cytokinins go in the plant?
most of Cytokinins= To the shoot apex. When apex is removed= cytokinins spreads evenly around the plant.
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What happened when scientists tested gibberellic acid on dwarf plants?
Grew taller= Gibberellic acid is responsible for plant stem growth
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Two things, shown by studies gibberellins cause?
1) growth in the internodes by stimulating cell elongation (by loosening cell walls). +. 2) cell division (by stimulating production of a protein that controls the cell)
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List 2 examples of how apical dominance could be an advantage to a plant?
1) plant growth towards the sunlight. 2) All buds grow at once=leaves shade other, decrease rate of photosynthesis
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state 4 features of 'plant hormones'
1) chemical messenger 2) used as a communication signal to target tissues 3)produced in very small quantities. 4) Transported from cell to cell via active transport + diffusion.
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Other cards in this set

Card 2

Front

where's Auxin produced?

Back

The apical meristem

Card 3

Front

What is auxin hormone responsible for?

Back

Preview of the front of card 3

Card 4

Front

What is the gibberellins hormone responsible for?

Back

Preview of the front of card 4

Card 5

Front

List 4 points relating to the mechanism for apical dominance.

Back

Preview of the front of card 5
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