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  • Water
    • Hydrogens attached to Oxygens
      • Covalent Bonds
      • Oxygen is more electro - negative than Hydrogen so electrons aren't shared equally
      • Hydrogen has a partially positive charge because electrons are pulled toward Oxygen
    • Diplole (uneven distribution of charge)
      • Any molecule that has a dipole is polar
    • Hydrophillic molecules attracted to charged parts of water because they're charged/polar
    • Hydrophobic Molecules don't mix with water .. no charge to attract water
      • Sometimes beneficial because when they're surrounded by water they will be pushed together creating stability in their structure. e.g. cell membranes
    • Solvent (polar/charged molecules dissolve in it)
      • Water molecules surround ion..
        • Seperating and breaking up the solid... it can now move and particles react as they can collide
      • Essentials dissolve in blood to be transported (glucose)
      • Digestive enzymes dissolve in water so they can collide with food
      • In the secretory system, urea is dissolved in water to allow us to remove it
      • Mucin in muceus dissolves in water to create a lubricant
    • Hydrogen bonds inbetween water molecules
      • Hard to break
        • High boiling point
          • Liquid at earth temp
            • Suitable transport medium and for organisms to live
              • High specific heat capacity so it stays a stable temp
                • Needs to absorb/lose heat to change temp
                  • Used as a coolant.. removes excess heat from the body
                • Provides us with a stable body temperature and organisms living in water plus a stable habitat temperature
    • Ice is less dense than water
      • Expands when cooled and freezes
        • Hydrogen bonds hold the water molecules apart at a distance
      • Useful for organisms living under ice as it insulates the water so they can survive
      • Changes in density causes currents in oceans which is important for circulating nutrients around oceans
    • Cohesion is where water molecues stick together as a result of hydrogen bonds between them
      • Xylem relies on cohesion to move water through the plant
      • Creates surface tension on water which can act as a habitat
    • Takes a big force to compress water molecules due to the hydrogen bonds keeping them apart
      • Water can take a a big force
        • Organisms living in it it are supported
        • Amniotic fluid in womb acts as a shock absorber
        • Large organisms can live in water
        • Plants use water for support (turgor)


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