1. Welcome to Unit 4: Homeostasis & Transport
Do Now:
1. Start a new section in your notebook: Unit 4
2. What do you need to get into and out of your body everyday in order to survive? Make your list as complete as possible.
We will be defining 2 very important words today – make sure your get them in your notes:
DIFFUSION EQUILIBRIUM

2. Cells do the same things!
Like take in food…
Mmmmm! Algae!

3. Cells do the same things!
And get rid of wastes!

4. But how? We have complex organ systems for all of that!

5. This unit is about how cells get things in and out of themselves.
But first – we need to know how things move around in solutions.
Then – we need to know how membranes (like the cell membrane) can affect that.
Finally, we need to know what cells can do when they use energy to change how things move.

6. Diffusion – The way of the Universe
Flashback: What is concentration?
Do things tend to move from a high concentration to a lower concentration or a lower concentration to a higher one?
Let’s do an experiment!

7. How is this picture of outer space similar to what we’re watching?

8. Diffusion!
Hot
Water
Cold
Water

9. It’s the same for stardust and molecules!
Diffusion: The movement of particles from an area of high concentration to lower concentration.
It’s caused by the random motion of atoms (aka thermal energy)
When the concentration of particles becomes equal in all parts of the environment, that’s called equilibrium.

10. Equilibrium
When the concentration of solute is equal throughout a solution.

11. An Experiment…
Describe how you could conduct a scientific experiment to measure how fast the scent in the corner diffused through the room.
Hypothesis?
Prediction?
Variables? What will you measure?
Control group?

12. Read All About it!
Section 5-1 “Diffusion” pp
SR #1, p. 100.