BiologyCode 5090
Diffusion and osmosis
What this topic asks you to be able to do
- Describe the function that water performs as a solvent within living things, in relation to digestion, excretion and transport
- Understand that diffusion and osmosis are powered by the kinetic energy that molecules and ions have as they move randomly
- Understand diffusion as the net movement of ions or molecules, driven by their random movement, from a place where they are more concentrated to one where they are less concentrated (i.e. down a concentration gradient)
- Investigate how diffusion is affected by various factors, limited to: distance, surface area, temperature and concentration gradient
- Understand that in osmosis, water molecules make a net movement through a partially permeable membrane, passing from an area with a higher water potential to one where the water potential is lower
- Know that plant support comes from water inside the cells exerting outward pressure on the cell wall
- Describe what osmosis does to plant and animal tissues, and explain why the water potential gradient and osmosis matter for water being taken up and lost
- Investigate and account for how plant tissues respond when placed in solutions of varying concentration, employing the vocabulary turgid, turgor pressure, plasmolysis and flaccid
- Investigate osmosis with the help of materials such as dialysis tubing