1.7 Water

• Explain how hydrogen bonds occur between water molecules

  • ● Water is polar molecule
  • ● Slightly negatively charged oxygen atoms attract slightly positively charged hydrogen atoms of other water molecules

  
• What are the 5 properties of water that are important in biology?

  1. Metabolite
  2. Solvent
  3. high specific heat capacity
  4. high latent heat of vaporisation
  5. strong cohesion between water molecules
• Why is metabolite property of water important in biology?

  Used in condensation / hydrolysis / photosynthesis / respiration
• Why is solvent property of water important in biology?

  1. Allows metabolic reactions to occur (faster in solution)
  2. Allows transport of substances eg. nitrates in xylem, urea in blood
• Why is high SHC property of water important in biology?

  ● Buffers changes in temperature

  ● As can gain / lose a lot of heat / energy without changing temperature

  1. Good habitat for aquatic organisms as temperature more stable than land
  2. Helps organisms maintain a constant internal body temperature
• Why is high latent heat of vaporisation property of water important in biology?

  ● Allows effective cooling via evaporation of a small volume (eg. sweat)

  ● So helps organisms maintain a constant internal body temperature
• Why is strong cohesion between water molecules property of water important in biology?

  1. Supports columns of water eg. transpiration stream through xylem in plants
  2. Produces surface tension, supporting small organisms (to walk on water)