Bio MCQ help

[dija]

Can Someone tell me what is the solute potential of the cell content phloem sieve tubes??
This Question is repeated in the 2 different papers and each time there was a different answer in marking scheme!
(Question 25 in October November 2003)
(Question 27 in May June 2008)

 

[alex906]

in the 03 paper it asked about solute concentration, which should be high as there is phloem sap in the sieve tubes, and in the 08 paper it actually asks about the solute POTENTIAL, so its a different question, this is a bit tricky as it can be high solute potential or low solute potential depending on which part of the plant it is. the source or the sink, but in a normal state, the solute potential should be low to start with cause when sucrose is pumped in then the solute potential will increase, if it is high to start with, then i dont think there'll will be a mass flow or a hydrostatic pressure difference. God Bless on your on coming exam! =)