B2.1 supplying the cell

• diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration
• in diffusion the particles move down a concentration gradient
• a concentration gradient is the difference in concentration between two places
• diffusion is a passive process as energy is not transferred
• diffusion continues until the particles are evenly spread
• diffusion in the body:

  particles enter and leave cells through the cell membrane from high to low concentration
• all our cells need oxygen and glucose for respiration. the blood carries these around the body they then diffuse out of the blood into the cell that need them
• waste products diffuse out of respiring cells, into the blood to be removed
• increasing the rate of diffusion

  1. decrease distance
  2. steeper concentration gradient
  3. increase surface area
  4. increase temperature
• osmosis is the net movement of water molecukes from a high to low water potential through a partially permeable membrane
• a solution is a solute + solvent