Translocation

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  • Created by: 10simso
  • Created on: 27-04-16 09:39
what does the phloem transport?
dissolved substances like sugars, sucrose and amino acids
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what is translocation?
an energy requiring process involving the movement of dissolved substances from source to sink to where they're needed in a plant via the phloem
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what are dissolved substances called?
assimilates
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what is the source?
where a substance is made and it has a higher conc.
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what is the sink?
the area where it is used up and is at a lower conc.
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give an example of source and sink using sucrose
-source is at the leaves (made by photosynthesis) -sink is other parts of the plant e.g. food storage organs and meristems (areas of growth) in roots, stems and leaves
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give an example of parts of the pant that can be both source and sink
-sucrose can be stroed in roots -sucose can be transported to the leaves from the roots to provide them with energy for growth -> roots are source and leaves the sink
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how do enzymes maintain a conc. gradient from source to sink?
by changing the dissolved substances at the sink (e.g. breaking them down) -> ensures that there is always a lower conc. at the sink than source
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give an example of this
-in potatoes, sucrose is converted to starch in sink areas, so there's always a lower conc. of sucrose at sink than in the phloem -> ensures that there is a constant supply of new sucrose reaching the sink -sucrose can be broken down into glucose
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what are assimilates?
substances that becomes incorporated into the plant tissue
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why are sugars transported as sucrose?
sucrose in soluble and metabolically inactive, so it doesn't get used up during transport
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what does the mass flow hypothesis involve?
1. source 2. sink 3. flow
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Card 2

Front

what is translocation?

Back

an energy requiring process involving the movement of dissolved substances from source to sink to where they're needed in a plant via the phloem

Card 3

Front

what are dissolved substances called?

Back

Preview of the front of card 3

Card 4

Front

what is the source?

Back

Preview of the front of card 4

Card 5

Front

what is the sink?

Back

Preview of the front of card 5
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