Movement of Substances (Biology)

• Diffusion


  is the random movement of particles from an area of high concentration to an area of low concentration until the particles are evenly spread out.

  
• Osmosis


  is the movement of water molecules from an area of high water potential to an area of low water potential through a partially permeable membrane

  
• Active transport


  can move substances into or out of cells against a concentration gradient

  
• Energy is needed


  for active transport

  
• Animal cells are enclosed by


  a partially permeable membrane

  
• When animal cells are put in a strong salt solution

  they shrink and wrinkle they become crenated

  
• When animal cells are put in water

  they swell up and burst

  
• A plant cell in strong salt solution becomes

  plasmolysed

  
• A plant cell in water


  swells and becomes turgid or firm

  
• The cellulose cell wall


  is tough and prevents the plant cell from bursting