Question

1. the molecules of solute in the illustration are moving through the cell membrane from top to bottom. indicate with labels which side of the membrane has a high concentration of solute and which has a low concentration.

osmosis

1. what does it mean that biological membranes are selectively permeable?
2. what is osmosis?
3. is the following sentence true or false? water tends to diffuse from a region where it is less concentrated to a region where it is highly concentrated.
4. when will water stop moving across a membrane?

match the situation to the description.
situation description

1. two solutions are isotonic. a. the solution is above strength in solute.
2. a solution is hypertonic. b. the solutions are the same strength.
3. a solution is hypotonic. c. the solution is below strength in solute.
4. on which side of a selectively permeable membrane does osmosis exert a pressure?

Explanation:

1. Molecules move from high to low concentration. So the top has high solute concentration and the bottom has low solute concentration.
2. Selectively permeable means only certain substances can pass through the membrane. This controls what enters and leaves the cell.
3. Osmosis is the diffusion of water across a selectively - permeable membrane from an area of high water concentration to an area of low water concentration.
4. False. Water diffuses from a region of high water concentration to a region of low water concentration (opposite of solute movement).
5. Water will stop moving across a membrane when equilibrium is reached, i.e., when the concentration of water and solutes is the same on both sides of the membrane.
6. b. Isotonic solutions have the same solute - concentration (same strength).
7. a. Hypertonic solutions have a higher solute - concentration (above strength in solute).
8. c. Hypotonic solutions have a lower solute - concentration (below strength in solute).
9. Osmosis exerts pressure on the side with lower water concentration (higher solute concentration) as water moves towards it to equalize the concentration.

Answer:

1. Top: High solute concentration; Bottom: Low solute concentration
2. Only certain substances can pass through the membrane.
3. The diffusion of water across a selectively - permeable membrane from an area of high water concentration to an area of low water concentration.
4. False
5. When equilibrium is reached (when the concentration of water and solutes is the same on both sides of the membrane).
6. b. The solutions are the same strength.
7. a. The solution is above strength in solute.
8. c. The solution is below strength in solute.
9. The side with lower water concentration (higher solute concentration)