biology - osmosis

• Osmosis

  water molecules move from an area of high water potential (water concentration) to an area of low water potential (low water concentration) through a partially permeable membrane
• Dilute solution

  high concentration of water (solvent)

  low concentration of sugar (solute)
• Solvent

  is able to dissolve other substances
• Solute

  Dissolved in the solvent
• Passive movement does not require energy
• Hypotonic solution

   A cell placed into a hypotonic solution will swell and expand until it eventually burst through a process known as cytolysis.

  water moves out of the cell

  
• Isotonic solutions

  When a red blood cell is placed in an isotonic solution, there will be no net movement of water. Both the concentration of solute and water are equal

  water moves in and out of the cell

  
• Hypertonic solution

  In a hypertonic solution, the net movement of water will be out of the body and into the solution. A cell placed into a hypertonic solution will shrivel and die (cell will shrink)

  
• Osmosis in plants

  water moves into cells by osmosis
• Vacuole swells and pushes against the cytoplasm during osmosis
• Cytoplasm pushes against cell wall creating pressure makes the cell rigid and firm
• When a cell is hypertonic the cell shrinks and dies and becomes plasmolysed

  
• when a cell is isotonic there is no net movement so is therefore flaccid

  
• When a cell is hypotonic the cell swells and the cell membrane becomes more permeable making the cell turgid

  
• A different number of oxygen molecules in the alveoli maintains respiration
• Molecules move from an area of high water concentration to an area of low water concentration
• movement of particles is passive
• Movement is random
• The turgid cells do not burst as the cell wall strengthens it through cellulose