WATER & ITS FUNCTIONS

• What is the polarity of water?

  No overall charge, although has both positive and negative poles so is describes as dipolar
• What type of bonding does water demonstrate?


  Hydrogen bonding between O and H of separate molecules of water- causes water molecules to stick together
• Specific heat capacity


  As water molecules stick together it takes more energy to separate them (due to H bonding)

  Therefore acts as a buffer to sudden temperature change making aquatic environment temperature-stable
• Latent heat vaporisation of water

  H bonding means it requires a lot of energy to vaporise 1g of water
• Why is sweating in mammals an effective means of cooling?


  As body heat is used to evaporate the water
• What is cohesion?


  The tendency of molecules to stick together
• Why does water have large cohesive forces?


  Hydrogen bonding
• What allows water to be pulled up the xylem vessel?

  cohesive forces due to H bonding
• What is surface tension?

  Water surface acts like a skin and allows small organisms like pond skaters to be supported
• What is the importance of water to living organisms?

  It is used in many processes:

  • used to break down molecules in hydrolysis
  • used as a solvent to dissolve other substances
  • evaporation cools organisms- allows them to control temperature
  • not easily compressed- provides support
  • transparent so aquatic plants can photosynthesise
• Where are inorganic ions found?

  in organisms where they occur in solution in cytoplasm of cells, in body fluids, as well as part of larger molecules
• What are functions of inorganic ions?


  specific function related to structure