Diffusion and Osmosis

1. Diffusion and Osmosis

2. is the movement of liquid or a gas molecules from a high concentrationto a low concentrationuntil the substance is evenly spread. important as it lets food and oxygen into a cell and waste products such as carbon dioxide out of the cell Diffusion

3. How does a scent spread through a gas? Molecules in solution tend to slowly spread apart over time. This is diffusion.

4. How Does a Dye Spread Through a Liquid?

5. How Does Heat Effect the Spread of Dye Through a Liquid?

6. osmosis is the movement of water molecules, from a region of high water concentration to a region of low water concentration across a selectively permeable membrane. Osmosis

7. a membrane controls what goes in and out of the cell. permeable means it allows substances to go through it. a selectively permeable membrane is a membrane with holes in it small enough for water to go through it easily. big molecules like starch can not fit through easily Selectively Permeable

8. Model of a Selectively Permeable Membrane Water Starch Small molecules, such as water can pass through it. Large molecules likestarch cannot pass through the membrane

9. Osmosis – what will happen? The water molecules pass both ways through the membrane The overall flow of water molecules is from a region with lots of water molecules to region of less water molecules. Until both sides have an evenly balanced water concentration. Water Starch Lots of water molecules Few water molecules

10. Which molecules will diffuse in each of the figures below? 1 2 3 4 5 6

11. ANSWERS 1 2 3 4 No Movement 5 6 No Movement

12. osmosis is the movement of watermolecules across a selectively permeable membrane. the membrane only allows small molecules to pass through it, large molecules can notpass through the membrane. water molecules move intothe region where there are less water molecules the water acts to even up the concentrationof water on either side of the membrane. Summary

13. in pure water– water will move inswelling the vacuole which pushes out against the cell wall. the cell does not burst because of the cell wall. Plant Cells in water Plant cell placed in pure water Water moves Into the cell

14. Plant Cell in Strong Sugar Solution In a strong salt or sugar solution– water will move outof the vacuole causing it to shrink. The cytoplasm can also shrink away from the cell wall. The plant cell is described as flaccid. Strong Sugar/Salt Solution

16. a red blood cell in pure water, water will move into the cell and the cell will burst(there is no cell wall to prevent this happening) in a strong salt/sugar solution water will move out and the cell will shrink Animal Cells in different solutions