1. DO NOW: Explain why putting an air freshener in the corner of a room will make the entire room smell good.
Day 13 AIM: What is diffusion and what does it have to do with concentration?

2. What is diffusion?
Diffusion is the movement of molecules from an area of high concentration to an area of low concentration.
An arrow is used to show the direction of diffusion
high conc. Low conc.

3. What is meant by Concentration?
Concentration refers to the ratio of solute to solvent in a solution.
Salute = material being dissolved
Solvent =material doing the dissolving
Solution= resulting mixture
Which glass is sweeter?
1package of Kool Aid per 1 Glass of Water
Higher
Concentration Of
Kool-Aid
2 packages of Kool Aid per 1 Glass of Water

4. Why does diffusion occur?
Diffusion occurs because molecules are always moving.
Because they are moving they tend to bump into each other.
This bumping causes them to move away from each other over time.
Over time these molecules become evenly distributed

5. Why does diffusion occur? (cont)
Because molecules are moving and bumping in to each other and moving away from each other, it is said that molecules move from areas of high concentration to areas of low concentration.
This stops when the molecules reaches an equilibrium. 15 20 15 10

6. Remember!!!
Molecules do not want to use energy. Just like a rollercoaster molecules will move from a high to a low.

7. So what does diffusion and concentration have to do with Biology?
Diffusion is a naturally occurring process.
Molecule move in and out of cell through this process because the cells need materials to perform the 8 life functions.
Some things that move into the cell are …..
Water
Oxygen
Nutrients (sub units: Glucose, Fatty Acids, Amino Acids & Nucleic Bases)
Some things that move out of a cell are …..
Cellular waste (Water and Carbon dioxide)
Cell products (Hormones)

8. The Cell Membrane (the bouncer)
Not every molecule can enter or leave the cell by diffusion.
These molecules are held back by the cell membrane.
The cell’s membrane acts like a net, those molecules that are small can easily fit through the small holes of the membrane, while large molecule are too big to fit through the hole and stay behind.

9. What can go through the membrane and what can’t?
What can Water Glucose Fatty acids Amino Acids Nucleic Base Oxygen Carbon Dioxide
What can’t
Salts
Starch
Lipids
Proteins
Nucleic Acids
Do you see a pattern?

10. Which way will the CO2 move?
Diffusion Practice
Cell
10% CO2
50% CO2
Which way will the CO2 move?

11. Which way will the O2 move?
Diffusion Practice
Cell
74% O2
15% O2
Which way will the O2 move?

12. Which way will molecules move?
Diffusion Practice
Cell
Urea is a small
molecule
8% Urea
(A small Molecule)
6% Urea
65% glucose
7% Glucose
Which way will molecules move?

13. Cell Diffusion Practice 4% starch 40% Starch
Starch is too big to move through the membrane.
4% starch
40% Starch
50% water
50% Water
Which way will molecules move?