1. OSMOSIS and DIFFUSION

2. Molecules are always moving
Molecules move randomly and bump into each other and other barriers

3. Concentration gradient
Concentration Gradient - change in the concentration of a substance from one area to another.

4. Diffusion
Molecules in solution tend to slowly spread apart over time. This is diffusion.

5. Diffusion
Movement of molecules from an area of high concentration to an area of lower concentration.
Factors that affect the rate of diffusion: size of molecules, size of pores in membrane, temperature, pressure, and concentration.

6. Diffusion [High] [Low] concentrated, high energy molecules
diffuse, low energy molecules

7. Diffusion will continue until equilibrium is reached
Diffusion will continue until equilibrium is reached. This means there will be an equal distribution of molecules throughout the space. This is why food coloring moves throughout a beaker of water; why odors smell strong at first and then disappear over time.
Equilibrium, a result of diffusion, shows the uniform distribution of
molecules of different substances over time as indicated in the
above diagram.

8. Osmosis
Osmosis is the movement of WATER across a semi-permeable membrane
At first the concentration of solute is very high on the left.
But over time, the water moves across the semi-permeable membrane and dilutes the particles.

10. Osmosis – A Special kind of Diffusion
Diffusion of water across a selectively permeable membrane (a barrier that allows some substances to pass but not others). The cell membrane is such a barrier.
Small molecules pass through – ex: water
Large molecules can’t pass through – ex: proteins and complex carbohydrates

11. Isotonic Solutions: If the concentration of solute (salt) is equal on both sides, the water will move back and forth but it won't have any result on the overall amount of water on either side. "ISO" means the same.

12. Hypotonic Solutions: The word "HYPO" means less, in this case there are less solute (salt) molecules outside the cell, since salt sucks, water will move into the cell. The cell will gain water and grow larger.

13. Hypertonic Solutions: The word "HYPER" means more, in this case there are more solute (salt) molecules outside the cell, which causes the water to be sucked in that direction. This is why it is dangerous to drink sea water - people marooned at sea will speed up dehydration (and death) by drinking sea water. This is also why "salting fields" was a common tactic during war, it would kill the crops in the field, thus causing food shortages.