1. Diffusion and Osmosis

2. Passive Transport Passive transport- movement of molecules across a cell membrane without energy input Refresh: Solute Object being dissolved Solvent Object doing the dissolving

3. Diffusion Diffusion: movement of molecules from areas of high concentration to areas of low concentration Concentration: number of molecules of a substance in a given volume Concentration gradient: difference of concentration of a substance from one location to another

4. Osmosis Osmosis: Diffusion of water Water moves across a semipermeable membrane from an area of high water concentration to an area of low water concentration

5. Types of Solutions Isotonic: cell has same concentration of dissolved particles as cell Water moves into and out of cell at equal rates and cell size remains constant

6. Types of Solutions Cont. Hypertonic: Solution has a higher concentration of dissolved particles than a cell Water concentration is higher in cell than outside Water flows out of cell, cell shrivels

7. Types of Solutions Cont. Hypotonic: solution has lower concentration of dissolved particles than a cell Water concentration is higher outside cell than inside cell Water flows into the cell, cell swells Cell may burst, this is called lysed

9. Plant Cells Plant cells prefer a hypotonic solution Cell wall provides more support and are less likely to lyse Plant cells at isotonic solutions are flaccid Plant cells at hypertonic solutions under-go plasmolysis The cytoplasm and plasma membrane begin to pull away from the cell wall Plant cell swells to point where it exerts a backward pressure, called turgor pressure This pressure prevents further uptake of water