Chapter 3 - Movements of Cells

• Diffusion

  1. Movement of particles from high concentration to low concentration down a concentration gradient

  2. Random movement
• Diffusion of oxygen and carbon dioxide


  In and out of cells
• Diffusion (examples)

  • Movement of nutrients from digestive system
  • Diffusion of water in small intestine into blood
• Solid


  No space to diffuse
• Liquid


  Has space to diffuse
• Gas


  Has space to diffuse
• Osmosis


  Movement of water molecules from high water potential (concentration) to low water potential down a concentration gradient through a partially permeable membrane
• Osmosis (examples)

  • Absorption of water from soil into cell
  • Water movement from large intestine into blood
• Active transport


  Movement of ions from low concentration to high concentration against a concentration gradient through a partially permeable membrane, requires energy
• Active transport (examples)


  • Transportation of sodium and potassium by sodium-potassium pump
  • Movement of photosynthesis products from leaf to fruit
• Carrier protein


  Facilitates active transport
• Hypotonic solution


  Water potential in solution is greater than in cell (more than 70%)
• Isotonic solution


  Water potential in solution is the same as in cell
• Hypertonic solution


  Water potential in solution is lower than in cell
• Animal cell in hypotonic solution


  Cell bursts (lysis)
• Plant cell in hypotonic solution


  Cell becomes turgid (swollen)
• Plant cell in hypertonic solution


  Cell becomes flaccid (shrivelled, crenation)