BIOL 101 LabBench Lab 1 Osmosis

The molar concentration of a sugar solution in an open beaker has been determined to be 0.3M. Calculate the solute potential at 27 degrees. Round your answer to the nearest hundredth.

-7.48 Calculation: Solute potential = −iCRT = −(1) (0.3 mole/1) (0.0831 liter bar/mole K) (300 K) −7.48

What is the water potential for this example? Round your answer to the nearest hundredth.

-7.48 Calculation: Water potential = −7.48 + 0, so water potential = −7.48

Will there be a net movement of water between two isotonic solutions?

No Water will move freely between the two solutions if they are separated by a selectively permeable membrane. However, there will be no net change in the concentration of water on either side of the membrane. Differences in solute concentration will allow you to predict net changes in water movement.

Why don't red blood cells pop in the bloodstream?

Red blood cells don't pop because the blood provides an isotonic environment for the cells.

There are two components to water potential: solute concentration and pressure. How do you think this fact affects the movement of water into and out of cells? For example, can two solutions that differ in their solute concentration be at equilibrium in terms of water movement? Can a solution with a molarity of 0.2 be in equilibrium with a solution with a molarity of 0.4?

Yes Two solutions will be at equilibrium when the water potential is the same in both solutions. This does not mean that their solute concentrations must be the same, because in plant cells the pressure exerted by the rigid cell wall is a significant factor in determining the net movement of water.

Which of the following statements is true for the diagram?

a. The beet core in beaker A is at equilibrium with the surrounding water

In beaker B, what is the water potential of the distilled water in the beaker, and of the beet core?

b. Water potential in the beaker = 0, water potential in the beet core = −0.2

Which beaker(s) contain(s) a solution that is hypertonic to the bag?

c. Beakers 1, 2, and 5

Which bag would you predict to show the least change in mass at the end of the experiment?

c. The bag in beaker 3

Arrange the beakers in order of the mass of the bags inside them after the experiment has run for 30 minutes. List the bag that loses the most mass first.

e. 2, 1, 5, 3, 4