1. Diffusion:
Molecules moving from a high concentration to a low concentration.
Example: Food coloring in water. The high concentration of color moves to the lower concentration, no mixing needed!

2. Link:

3. Diffusion: More examples
Water soaking
into the soil
after the rain
Perfume flowing through a room
Nutrients moving from your blood into your body cells

4. Another example of diffusion:
Osmosis: diffusion of water through a membrane, like in every cell of your body!
Water moves in and out of cells all the time, trying to make the inside of the cell the same concentration of water as the outside.
You need to drink enough water to keep your cells hydrated!

5. Link:

6. Lots of sugar means less water, so this side has a low concentration of water.
Water moves from the high concentration to a low concentration. The sugar is too big to move.
“Selectively permeable or semi-permeable membrane” means some stuff, like water, can get in and out, but not big things like sugar.

7. If….then…
If you put cells in pure 100% water, then water will go into the cells (High conc. outside to low concentration inside the cell)
***Too much water can pop cells that don’t have a cell wall to protect them!
If you put cells in a solution with lots of salt, sugar, or other chemicals, then water will leave the cells.

8. Blood cells placed in pure water: They may pop!
Cells in salt water
Blood cells placed in pure water: They may pop!
Normal red blood cells

10. In this picture a red blood cell is put in a glass of distilled water (all water with no salt or sugar in it). 
Because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS.

12. What happens… …if you put a freshwater fish into the ocean?
…the salt water of the ocean will cause all the water in the fish’s cells to diffuse out, and the fish will become dehydrated and die!

13. What happens…
…if you put an ocean fish into a glass of drinking water?
…the fish’s cells will absorb too much water, and they may start bursting like balloons!

14. What happens…
…is it a good idea to drink sugary soda when you are thirsty?
NO-the sugar water will pull more water out of your cells, and make you even MORE thirsty.
***Soft-drink companies know this, and add sugar and salt to drinks to make you want more!

15. Elodea Plant in a fish tank

16. Elodea Plant in a fish tank

17. Elodea cells in normal pond water

18. Elodea in salt water
Notice the empty space between the cell wall and the green chloroplasts!
Most of the water left the cells!

19. Pond Water
Salt Water

20. Normal cells are full of water, leaves and stems are “crisp” when you break them, not wilting.

21. Normal plant cells have “Turgor Pressure”, which is the pressure of water pushing on the cell wall. It keeps the plants firm and pointed up at the sun.

22. Cells that have lost water will make the plant easy to bend, plants cannot survive long without enough water.
Cells in Salt Water

23. Is this celery in salt water or pure water?
Answer….
Salt water! It has lost water and become soft and bendable.

24. Which one is salt water?
Salt water
Fresh water