Cell Membranes and Transport

Hands-On Labs, Inc. Version 42-0033-00-01

Exercise 1: Diffusion

Observations

Data Table 1: Rate of diffusion in different temperatures
ºC Minutes

Temperature Initial
Temp. Initial
Color
5
10
15
20
25
30
60

Cold

Ambient

Hot
Questions

A. Write a one-paragraph analysis of the results for the procedure. Provide reasons for the difference in the rate of diffusion at the different temperatures.

B. Did the sizes of the molecules affect their movement?

C. Give an example of diffusion between: a solid and a liquid; a gas and a liquid; between two different solids.

Exercise 2: Osmosis
Observations

DataTable 2: Potato Mass

Contents in Test
Tube
Initial Mass of Two Potato Strips

Final Mass of Two Strips

Mass
Difference

% Change in
Mass Class Average Percent Change in Mass (if available)
a) Distilled Water
b) 1.0 M Sucrose
c) 0.8 M Sucrose
d) 0.6 M Sucrose
e) 0.4 M Sucrose
f) 0.2 M Sucrose

Questions

A. Describe how the potato cylinders changed in their turgidity. Identify which of the solutions were isotonic, hypertonic, and hypotonic in relation to the potato.

B. What would happen to a red blood cell placed in distilled water? Why?

C. Create a graph of your experimental data by plotting the percent change in potato mass against sucrose molarity. Label the x-axis as “Molarity of Sucrose,” and the y-axis as “% Change in Mass.”

D. Determine the molar concentration of the sucrose contained in the potato strips by using the graph created in Question C. At the point where the molar concentration of the sucrose in the potato would be isotonic to the sucrose, there would be no net change in the potato mass. On the graph this is located at the 0% change. Draw a line from this place on the y-axis to intersect the line. From the line draw a line down to the x-axis to find the molarity.