Diffusion and Osmosis- SAQs.docx

**[Questions]** 1. What is diffusion? Movement of molecules from a region of higher concentration to a region of lower concentration. 2. Define Active Transport. Movement of molecules from an area of low concentration to an area of high concentration using energy. 3. Over what type of membra...

**[Questions]** 1. What is diffusion? Movement of molecules from a region of higher concentration to a region of lower concentration. 2. Define Active Transport. Movement of molecules from an area of low concentration to an area of high concentration using energy. 3. Over what type of membrane does osmosis occur? A selectively-permeable membrane 4. Define selectively permeable membrane. Allows the entry of some substances and prevents the entry of others. 5. Define osmosis. The movement of water molecules across a selectively-permeable membrane from a region of high concentration to a region of low concentration. 6. Does osmosis require external energy? No, it is passive 7. What is isotonic solution? Solution that is the same concentration as the cytoplasm in the cell.  8. What is hypotonic solution? Solution that is less concentrated than the cytoplasm in the cell. 9. What is hypertonic solution? Solution that is more concentrated than the cytoplasm in the cell. 10. Define turgor pressure. The force of the cytoplasm and vacuole pushing out against the cell wall. 11. What is the function of turgor pressure? It provides strength to the cell. 12. What is plasmolysis? When the cell-membrane shrivels away from the cell wall. 13. Give an example of osmosis in food preservation. Fish and meat may be stored in a salty solution.  **[Experiment Questions: ]** 1.  Define osmosis. The movement of water molecules across a selectively-permeable membrane from a region of high concentration to a region of low concentration 2. Name the material you used to act as a selectively permeable membrane? Visking tubing 3. Why are the tied ends of the visking tubing kept out of the water?  To ensure that there is no leakage. 4. How do you know osmosis has happened? The mass and 'fullness' of the visking tubing containing the sucrose solution had increased after the fifteen minutes. 5. If an animal cell was placed in the sucrose solution what would happen to it? Water would move out of the cell as a result of osmosis and the cell would shrivel and die.