Movement into and out of cells.

• Diffusion

  The net movement of particles from a region of high concentration to a region of low concentration.
• Osmosis

  The movement of water molecules from a region of high water potential to a region of low water potential.
• Active transport

  The movement of particles from a region of low concentration to a region of high concentration using the energy of respiration.
• Factors affecting rate of diffusion:

  • Concentration
  • Temperature
  • Surface area
  • Distance
• When water molecules moves into a plant cell by osmosis, the cell enlarges and becomes turgid. The pressure against the cytoplasm is called turgor pressure.
• When water molecules move out of a plant cell, the cell becomes soft and its cytoplasm detaches from its cell wall.
• When water molecules enters an animal cell, it rapidly increases its volume and pressure, causing the cell to burst. Without the presence of the cell wall the cytoplasm will rupture.
• When water moves out of an animal cell, it will rapidly decrease in volume and shrink.