OSMOSIS
IN ACTION
Note to teacher: The following is a student worksheet. If you want to print this out, click on the title above for a better version.
PROBLEM: What affect does water have on a permeable membrane?
HYPOTHESIS: (Will vary)
MATERIAL:
|
1. rubber band |
5. dialysis tubing |
|
2. food coloring |
6. distilled water |
|
3. beaker |
7. test tube |
|
4. base stand w/clamp |
PROCEDURE :
1. Place two drops of food coloring in 20 ml of concentrated salt solution in a large test tube.2. Place firmly a rubber band around the permeable membrane after placing it over the mouth of the test tube.
3. Invert the test tube into a beaker of distilled water. (See diagram)
4. Observe closely the solution in the test tube.
CONCLUSION: (Student will formulate their conclusion by answering the following question)
1. What happened to the dyed salt water?2. What happened to the distilled water?
3. Explain what eventually happened to the solution in the test tube and the water in the beaker? Why?
Osmosis
EVALUATION (REVIEW) :
1. Water (passive transport) passes through a permeable membrane by diffusion called osmosis.2. Osmosis need no assistance (energy) for water to pass through a membrane, passive transport takes place.
3. The cell membrane spaces are large compared to the size of some particles, such as water.
4. Cell permeability in osmosis allows particles to cross the membrane from a region of low concentration (water) to a region of high concentration (solute of salt water) in the cell.
5. Therefore, the same number of water molecules are the same inside and outside the cell, putting the cell in a state of equilibrium.
CLOSURE:
Good lesson today! However, tomorrow, your written assignment is:
Identify: hyper-, hypo-, isos-, and hyperosmotic, hypoosmotic, isosmotic and osmotic pressure
For other resources click in to the following WEB SITES:
Cell Membrane Transport: