DIFFUSION ACTIVE TRANSPORT AND OSMOSIS


  • Created by: Molly Amy
  • Created on: 27-07-19 13:57
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  • active transport
    • what is it - its the movement of particles against and concentration gradient. using energy released during respiration
      • like diffusion and osmis it is uses to move substance in and out of cells
        • active transport is used in the digestive system when their is low concentration of nutrients in the gut but high concentration of nutrients in the blood
          • 1. when high concentration of nutrients in the gut they diffuse into blood
            • 2 sometimes theres lower concentration of nutrients in the gut than there is blood this is the wrong way round !!!!!!!!!!!!!!
              • 3.  active transport allows nutrients to be taken into the blood this is essential to stop us starvining but active transport need energy from respiration to make it work
    • 4 factors affect the movement of substances
      • 1. surface area to volume
  • this is a special case of diffusion
    • to decribe osmosis = the net movement of water molecules across a partially permeable membrane from a region of lower solute concentration to a region of higher solute concentration
    • osmosis
  • water moves into and out of cells by osmosis
    • tissue fluid surrounds the cells in the body
      • this is water oxygen and glucose - it is squuzed out of blood capillaries to supply the cells with what they need
        • the tissue fluid will have a different concentration in tissue fluid to fluid inside cell, this mean water will either move into the cell from tissue fluid or out of the cell by OSMOSIS
          • IF CELL IS SHORT OF WATER THE SOLUTION INSIDE THE CELL WILL BECOME QUITE CONCENTRATED SO WATER WOULD MOVE INTO THE CELL AND WILL BE DRAWN OUT IF IT HAS LOTS OF WATER BY OSMOSIS
  • diffusion
    • what is diffusion = gradual movement of particles from places where there are lots of them to places where there is fewer of them
  • diffusion does not require engery it is a passive process
    • it happens in gases and liquids
      • cell membranes they hold cell together but also let stuff in and out
        • sustances move in and out by diffusion, osmosis and active transport
          • only small things can diffuse in and out of cell membrane
            • things like glucose,amino acids,water,  oxygen big things like starch and protein can not
  • diffusion and osmosis tests
    • potato cylinder
      • potato cut up into different sugar soluation sand pure water
        • if the cylinders have drawn water in by osmosis the potato will be longer if the water water has been drawn out the the potato would have shunk
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