Movement in and Out of cells

• Diffusion: Net movement of particles from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement.
• Substances move into and out of cells by diffusing through the cell membrane
• Water diffuses through the partially permeable membranes by osmosis
• Water moves in and out of cells by osmosis through the cell membrane
• Osmosis: Net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution) through a partially permeable membrane
• Factors affecting diffusion:

  • Surface area
  • Temperature
  • Concentration gradient
  • Diffusion distance
• Factors affecting diffusion

  Temperature:

  • Higher temperature -> More kinetic energy -> faster diffusion
• Factors affecting diffusion

  Surface area:

  • Larger SA -> mor space for molecules to move through -> faster diffusion
• Factors affecting diffusion

  Distance:

  • Shorter diffusion distance -> faster diffusion
• Factors affecting diffusion

  Size of molecule:

  • Smaller size/ mass -> less friction/ collisions -> faster diffusion
• Keeping water balanced:

  Plant cell in:

  Pure water: Turgid (normal)

  Balanced: Flaccid

  Salt water: Plasmolyzed

  
• Keeping water balanced:

  Animal cell in:

  Pure water: Lysed

  Balanced: Normal

  Saltwater: Shrivelled