3.1.7 Water

• Water is a major component of cells
• Hydrogen bonds occur between water molecules because water is a polar molecule. It is also slighty negative charged oxygen atoms attract slightly positively charged hydrogen atoms of other water molecules
• 5 properties of weater that are important in biology:

  1. Metabolite
  2. Solvent
  3. High specifc heat capacity
  4. High latent heat of vaporisation
  5. Strong cohesion between water molecules
• Metabolite is important in biology because it is used in condensation, hydrolysis, photosynthesis and respiration
• Solvents are important in biology because it allows metabollic reactions to occur and it also allows the transport of substances e.g, nitrates in the xylem and urea in blood
• High specific heat capacity is important in biology because it buffers temperature changes. It can also gain and lose a lot of heat and energy without changing temperature. This provides a habitat for aquatic organisms as temperature is more stable than lands and it helps organisms maintain a constant internal body temperature.
• High latent heat of vaporisation allows effective cooling via the evaporation of a small volume e.g, sweat so it helps organisms maintain a constant internal body temperature
• Strong cohesion between water molecules supports columns of water e.g, transpiration stream through xylem in plants. It also produces surface tension, supporting small organisms.