Lab 14 Review
Name:
Osmosis
Instructions: Log in to www.explorelearning.com Open the Osmosis Gizmo and follow the
instructions below.
Vocabulary:
1. Choose one a double layered membrane that surrounds the cell and also called the plasma
membrane. Regulates what enters and exits the cell.
2. Choose one a measure of how much a given substance is mixed with another substance.
3. Choose one The spontaneous net movement of particles from area of high concentration to an
area of low concentration.
4. Choose one a state of balance in which there is little or no total change. When particles in two
regions move back and forth between regions, but the total number of particles in each region
remains roughly constant.
5. Choose one the movement of water molecules across a semipermeable membrane from an area
of high concentration to an area of low concentration.
6. Choose one A membrane that allows certain substances to pass through but does not allow the
passage of other materials.
7. Choose one a substance that is dissolved in another substance to form a solution
8. Choose one a liquid that dissolves a solute to form a solution.
A cell membrane is a thin “skin” that surrounds a cell. It is a
semipermeable membrane, which means that some particles pass
through the membrane easily while others cannot. The Osmosis Gizmo™
portrays a cell (red square) in a solution of purple solute particles
dissolved in green solvent particles. Press Play (
) and observe.
9. Which particles can pass through the cell membrane? Choose one
10. Which particles cannot pass through the cell membrane? Choose one
11. Click Reset (
Choose one
), and then click Play again. What do you notice about the size of the cell?
Activity A:
Directions: The concentration of a solute is the amount of solute particles in a given amount of
solvent. To calculate percentage concentration, divide the number of solute particles by the total
number of particles (solute + solvent), and then multiply by 100:
% concentration = (solute ÷ total particles) × 100
12. Select the DESCRIPTION tab. Click Reset. Set the Solute outside to 10 and check that the Initial
cell volume is 40%. (Note: The cell volume is expressed as a percentage of the container size.)
a. How many solute particles are found inside the cell?
b. How many solvent particles are found inside the cell?
c. What is the total number of particles inside the cell?
Outside?
Outside?
Outside?
d. What is the % concentration of solute inside the cell?
e. What is the % concentration of solute outside the cell?
13. Click Play, and observe the numbers shown on the DESCRIPTION pane. How does each number
change over time?
 Solute particles inside? Choose one
 Solute particles outside? Choose one
 Solvent particles inside? Choose one
 Solvent particles outside? Choose one
 Solute concentration inside? Choose one
 Solute concentration outside? Choose one
14. Click Reset. Check that the Solute outside is 10 and the Initial cell volume is 40%. To calculate
the solvent concentration, divide the number of solvent particles by the total number of
particles, and then multiply by 100. (Note: The Gizmo only displays the solute concentrations.)
a. What is the solvent concentration inside the cell?
b. What is the solvent concentration outside the cell?
c. Where is there a higher solvent concentration?
d. Do you think the cell will get larger or smaller?
e. Click Play to confirm your predictions. Were you correct?
15. You have observed examples of osmosis—the diffusion of a solvent (such as water) across a
semipermeable membrane. Summarize what you have observed by filling in the blanks in the
following paragraph:
During osmosis, solvent particles move from an area of choose one concentration to an area of
choose one concentration. When there is a higher concentration of solvent particles inside the cell,
most solvent particles will move choose one the cell and the cell will choose one. When there is a
higher concentration of solvent particles outside the cell, most solvent particles will move
choose one the cell and the cell will choose one.
Activity B: Effect of cell volume
16. Select the BAR CHART tab, and turn on Show numerical values. With the Solute outside set to
5, predict whether the cell will swell, shrink, or stay the same with each of the following Initial
cell volume settings. Then use the Gizmo to check each prediction.
Predictions:
20% choose one
50% choose one
60% choose one
Actual results:
20% choose one
50% choose one
60% choose one
17. Why do solvent particles flow into the cell when the initial volume is below 50%?