2. Movement IN and OUT of Cells

3. Substances move in and out through the cell membrane Moving from high to low concentration DOES NOT REQUIRE ENERGY by the cell: Called Passive Transport

4. When the cell USES ENERGY to transport materials in or out: called Active Transport During active transport, molecules (like carbs., H ₂ 0, O ₂, CO ₂ ) move from LOW to HIGH concentration

5. Moving Water Osmosis = The diffusion of water across a semi-permeable membrane

6. Remember that… Diffusion = movement of molecules from high to low concentration Semi-permeable membrane = allows only certain things in or out Concentration gradient = the unequal distribution of molecules

7. So …. osmosis is when water molecules move from where there is a lot to where there is less by going through a semi-permeable membrane

8. 3 Types of Solutions Isotonic = concentration of dissolved substances is the same inside and outside of the cell – therefore … water moves EQUALLY IN and OUT

9. Hypertonic = concentration of dissolved substances is greater outside than inside of the cell – therefore … water moves OUT of the cell

10. Hypotonic = concentration of dissolved substances is greater inside than outside of the cell – therefore … water moves INTO the cell