1. Today’s Learning Goals
1. A) Describe the process of diffusion.
1. B) Explain how osmosis occurs.
1. C) Compare and contrast osmosis and diffusion.

2. Diffusion Molecules – Building blocks of matter. Diffusion:
The movement of molecules from an area of high to an area of low concentration.
•Ex: Perfume Diffusing through a room. •Ex: Dye diffusing through water

3. Diffusion Notes
Particles travel from areas where it’s crowded to areas where it’s less crowded.
High concentration arrow low concentration
High density arrow low density
Diffusion happens within and between living cells.
Passive Transport = Cells do not need to use energy for diffusion.

4. X x x
x x
X x x
X x x x x x x x
xxxx x x xxxx x
X x x x x x x x x

5. What speeds up the rate of diffusion?
Add heat
Heat Energy- Causes molecules to vibrate

6. Diffusion Lab Date: 11/13/09 – Denture Cleanser
Hypothesis: If, then form
Observation: Quantitative/Qualitative
Process: Circle one
Diffusion or Osmosis
Passive or Active Transport

7. What is a cell membrane? A thin envelope that surrounds a cell
Lets things in & out.
A membrane can be:
Impermeable --- Substances cannot pass thru
Permeable --- Substances can freely pass thru
Semi-Permeable ---- Allows some substances

8. Osmosis
Osmosis: The diffusion of water across a semi-permeable membrane.
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* In diffusions/osmosis, molecules always move toward a low concentration

9. Osmosis Notes
Osmosis is the diffusion of water through a semipermeable membrane.
Osmosis is important to cell functions.
It also occurs in plant and animal cells
Semipermeable means only certain substances can pass through
Water is made up of particles called molecules.
Ex: Red blood cells burst in pure water – particles move from outside (more dense) to inside (less dense). Cell would fill up and burst.

10. Osmosis What is the concentration of the
water compared to that of the cell?
A. Equal Concentrations
B. Water is Low Concentration
C. Water is High Concentration
A B C

11. Diffusion/Osmosis Lab
11/16/09 – Tea Bag
Hypothesis: If, then form
Observation: Quantitative/Qualitative
Process: Circle one
Diffusion or Osmosis
Passive or Active Transport

12. Other Labs on diffusion and osmosis
11/17/09 – Carrot
11/18/09 – Gobstoppers
11/19/09 – Gummy Bears