Osmosis experiments

• All living things are made of cells which are differentiated to perform different functions
• Substances move into or out of the cell and enzymes are catalysts contributing to cell metabolism
• Selectively permeable


  The property of a membrane that controls the movement of molecules depending on their size
• Substances that can pass through the microscopic holes in a selectively permeable membrane


  • Smaller molecules like water and glucose
• Substances that cannot pass through a selectively permeable membrane


  • Larger molecules like starch, sucrose
• Osmosis experiment with Visking tubing

  1. Water moves by osmosis from the high water concentration (dilute solution) in the beaker into the low water concentration (concentrated solution) in the Visking tubing across the membrane, increasing the volume of liquid in the Visking tubing, which forces liquid up the capillary tube

  2. Water moves by osmosis from the high water concentration (dilute solution) in the Visking tubing into the low water concentration (concentrated solution) in the beaker across the membrane, decreasing the volume of liquid in the Visking tubing, which lowers the level of liquid in the capillary tube

  3. Water moves equally from inside the tubing to outside across the selectively permeable membrane. There is no net movement of water in any direction as the concentration is equal on both sides so the level of water in the capillary tube remains the same