= -miRT
m = molarity of solution
i = ionisation constant (= 1.0 for sucrose)
R = gas constant (0.0083MPa/mol degree)
T = absolute temperature (= oC + 273)
Unit
62212
PLANT PHYSIOLOGY 1
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(1) Briefly define each of the following terms:
water potential
aquaporins
root pressure
stomatal resistance
osmosis
differentially permeable membrane
cohesion
(2) Outline three major functions of water in plants.
(3) Compare the roles of diffusion and bulk flow in the movement of water and solutes in plant tissues.
(4) Discuss the synthesis, role and composition of the cuticle in plants.
(5) Describe three characteristics of xylem conducting vessels and tracheids which make them suited to their role in water movement in plants?
(6) Briefly discuss the role of water potential gradients in driving the process of transpiration.
(7) Outline the three major components of total water potential and briefly explain what is meant by each.
(8) Briefly outline four major functions of water in plants.
(9) (a) What is the water potential of a slice of plant tissue in which the osmotic potential of the vacuole is -0.32 MPa and the pressure potential is 0.07 MPa? Show all calculations.
(b) If this same tissue slice is placed in an external sucrose solution with a concentration of 0.10 M and a temperature of 26C at atmospheric pressure, what will happen to the weight of the tissue? Show all calculations.
The following equation may assist you:
m = molarity of solution
i = ionisation constant (= 1.0 for sucrose)
R = gas constant (0.0083MPa/mol degree)
T = absolute temperature (= oC + 273)