Of what value to a plant is the ability to lose water through transpiration?

Transport in plants...Multiple choice - please help?

• 1. Which statement is the best explanation of why sucrose rather than glucose is transported by phloem? A. Sucrose can pass through plant cell surface membranes more easily. B. Sucrose is a disaccharide and is more easily converted to starch. C. Sucrose is a non-reducing sugar, so is less reactive. D. Sucrose synthesis requires less energy. 2. A researcher, who wants to study the composition of a plant's sap, inserts a capillary tube into the phloem. What causes the sap to flow out of the tube? A. capillarity B. hydrostatic pressure C. root pressure D. transpiration stream 3. Water is transported from roots to stem to leaves. Measurements of the water potential of the cells at points P, Q and R were taken. P - leaves Q - stem R - roots Which value for water potential (in MPa) are consistent with the cohesion-tension hypothesis? A. P= -1 Q= 0 R= -2 B. P= -2 Q= 0 R= +2 C. P= -4 Q= -2 R= 0 D. P= 0 Q= -2 R= -4 Thanks for any help!! I have searched the Internet looking for sites to help me answer these but haven't found anything. If you know any good sites, let me know:) Thanks!!!

• Answer:

  A B- transpiration stream only causes water to move through the plant Dont know the last one