1. Osmosis Notes

2. Osmosis 1. The Cell Membrane
a. Cells are not entirely closed off from their surroundings.
b. The cell membrane has spaces that allow certain materials like oxygen, water, and carbon dioxide to flow through.
c. It is important for these molecules to go in and out of the cell so that the cell can stay alive.
H2O

3. Osmosis 2. How it Works
a. Osmosis occurs when water crosses over the cell membrane.
b. Water will move from areas of high concentration to areas of low concentration. Does that sound familiar? You learned about diffusion in the unit about particle motion.
c. Osmosis is the diffusion of water across a cell membrane.
Diffusion. Notice that the red molecules are able to move across the membrane. This shows diffusion.
Osmosis. Notice that the water on the right is higher than on the left. The water diffused across the membrane making this an example of osmosis.

4. Salt Sucks Osmosis 3. How it Works A simple rule to remember is:
Salt is a solute, when it is concentrated inside or outside the cell, it will draw the water in its direction. This is also why you get thirsty after eating something salty.

5. Osmosis Take a Look
Click the links below to learn a little more about osmosis. Try the practice quiz from the Animation: How Osmosis Works link when the video is over.
Animation: How Osmosis Works
Jake Teaches Osmosis
Adding Salt