Active transport, diffusion, osmosis

• Diffusion


  Net movement of particles from an area of high concentration to an area of low concentration
• Diffusion


  1. Molecules move about randomly

  2. Happens in gases and liquids

  3. Takes place through materials

  4. Partially permeable membrane allows some molecules to diffuse through (e.g. water, glucose, amino acids) but not others (e.g. proteins, starch)
• Diffusion

  • Passive process, doesn't require energy
• Concentration gradient

  The bigger the difference in concentration, the quicker particles diffuse
• Temperature

  Higher temperatures give particles more energy, they move around faster, so diffusion is quicker
• Surface area

  Larger surface area leads to a higher rate of diffusion
• Active transport

  Movement of molecules against their concentration gradient (from lower to higher concentration), requires energy from cellular respiration