Osmosis

• What is osmosis?

  Osmosis is the diffusion of water molecules across a partially permeable membrane from an area of higher water potential to an area of lower water potential. 
• What is high water potential?

  A solution has a high water concentration
• What is low water potential?

  When a solution a low water concentration
• What is a hypotonic solution?

  A solution with a higher water potential than the cell.
• What happens to an animal cell in a hypotonic solution?

  Water moves into the animal cell & and it swells and bursts (cell lysis)
• What happens to a plant cell in a hypotonic solution?

  Water moves into the plant cell and it swells and becomes turgid
• What is an isotonic solution?

  A solution that has the same water potential as the cell
• What happens to cells in a isotonic solution?

  Nothing happens to animal or plant cells as there is no net movement of water
• What is a hypertonic solution?

  A solution that has a lower water potential than a cell
• What happens to an animal cell in a hypertonic solution?

  Water moves out the cell & and it shrinks (crenation)
• What happens to a plant cell in a hypertonic solution?

  Water moves out of the cell & the plant cell shrinks (plasmolysed)
• How does temperature affect osmosis?

  Higher temperature - the particles have more kinetic energy & can diffuse faster
• How does water potential gradient affect osmosis?

  The steeper the gradient, the faster the rate of osmosis
• How does thickness of membrane affect osmosis?

  Thin membrane = shorter distance water molecules have to travel = faster rate of osmosis
• How does surface area affect osmosis?

  Large surface area - more molecules can diffuse at once = faster rate of osmosis