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Science - Biology
Standard 2 Objective 3
1 class periods of 70 minutes each
Students will perform two experiments using bags made of dialysis tubing. One demonstrates diffusion, the other osmosis.
Description: Students will perform two experiments using bags made of dialysis tubing. One measures the movement of iodine across the membrane into a bag filled with starch solution, where it turns black. This is an example of diffusion, water is not involved. The other experiment measures the movement of water (therefore, osmosis) into a bag of sugar.
Students should be aware of the definitions for osmosis and diffusion. They should also understand that living membranes are able to let particles of a certain size through and can actively transport molecules that they need either inside or out. The package the dialysis membrane comes in should say what size particle can pass through it. Dialysis membranes, being non-living are unable to actively transport molecules against the osmotic pressure.
1. Students collect and record data 4
2. Students correctly answer analysis questions ..4
Lesson Design by Jordan School District Teachers and Staff.