DIFFUSION AT WORK Names________________________

Introduction: IN this performance test you will design an experiment to test ONE factor that affects the speed of diffusion. You need to make sure you have a control and a place to record all your data. Your teacher has provided you with materials but you will not use all of them.

Hypothesis:

Materials:

Procedure:

Data:

Analysis:

1. What variables were present in this experiment?

2. Describe the control:

3. When might you want to speed up diffusion?

4. Conclusion:

Cell Membrane Simulation

A starch solution is relatively clear. An iodine solution is a rust color. When mixed, the solution is purplish. You are to design an experiment to test the permeability of a “cell membrane,” in this case, a plastic bag.

General Guidelines: you’ll want starch on one side of the bag and iodine on the other. Make sure the bag is tied off.

Hypothesis:

Procedure:

Data:

Analysis:

Compare the color of the iodine and starch at the start and the conclusion of the experiment.

Which molecules crossed the membrane? What is your evidence?

Evaluate whether or not a plastic bag is an adequate model of a selectively permeable membrane.

Osmosis Simulation

Dialysis tubing is a selectively permeable membrane. It will allow water to pass through, but not salt.

General Guidelines: You’ll want to place salt water inside the tubing or outside the tubing. Make sure you have fresh water on the other side and that the tubing is tired off well. You also need to figure out a way to determine whether water entered or exited the bag. (Hint – I have scales out for you.)

Hypothesis:

Procedure:

Data:

Conclusion:

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