4. Plant cells are surrounded by semipermeable membranes that allow water to pass through, but not the cellular fluids.

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4 Plant Cells Are Surrounded By Semipermeable Membranes That Allow Water To Pass Through But Not The Cellular Fluids 1 (58.79 KiB) Viewed 54 times

4. Plant cells are surrounded by semipermeable membranes that allow water to pass through, but not the cellular fluids. The redwoods of California can grow to as high as 105 m (350 ft). At the top of the trees, leaves are constantly losing water to the atmosphere. This results in an increased solute concentration in the fluids in the leaves. (a) Estimate the osmotic pressure required to draw water up from the roots to the top of a 105 m tree. Hint: the pressure of a column of water of a given height is p=pgh where p is the density of water, g is the acceleration due to gravity, and h is the height of the column. (b) What is the concentration of the solute in the leaves in order to cause this osmotic pressure? Assume that T = 298 K. Homework 5. Lysozyme extracted from chicken egg white has a molar mass of 13,930 g mol-1 Exactly 0.1 g of this protein is dissolved in 50 g of water at 298 K. If the vapour pressure of pure water is 3.17 kPa at 298 K, calculate (a) the vapour pressure lowering (8.19 x 10-6 kPa) (b) the depression in freezing point if k, = 1.86 K kg mol-? (2.67 x 10-4 K) (c) the elevation of the boiling point if k, = 0.51 K kg mol-? (7.3 x 10-5 K) (d) the osmotic pressure (0.356 kPa)