MollyBarkerX
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What are the 3 points of evidence for mass flow associated with the companion cell and then what is the evidence for mass flow associated with the phloem?
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Renn0
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Evidence of mass flow associated with the phloem are that:
1) When the phloem is broken sap flows out indicating an outward pressure
2) There is a higher concentration of sugar in the source (leave cells) than in the sink (root cells)
3) Increases in sugar conc. in the leaves lead to a similar increase in sugar conc. in a phloem
4) Flow in the phloem occurs in the day but ceases at night
Evidence for mass flow associated with the companion cell:
1) companion cells have lots of mitochondria and produce lots of ATP (for active transport of sugars, therefore creating low water potential in phloem)
I'm not sure about the other 2 points of evidence. Perhaps that companion cells surround the seive tube elements? Hope this helped though
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MollyBarkerX
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(Original post by Renn0)
Evidence of mass flow associated with the phloem are that:
1) When the phloem is broken sap flows out indicating an outward pressure
2) There is a higher concentration of sugar in the source (leave cells) than in the sink (root cells)
3) Increases in sugar conc. in the leaves lead to a similar increase in sugar conc. in a phloem
4) Flow in the phloem occurs in the day but ceases at night
Evidence for mass flow associated with the companion cell:
1) companion cells have lots of mitochondria and produce lots of ATP (for active transport of sugars, therefore creating low water potential in phloem)
I'm not sure about the other 2 points of evidence. Perhaps that companion cells surround the seive tube elements? Hope this helped though
Thankyou!!
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