1.7 Water

Question 1

Explain how hydrogen bonds occur between water molecules

Answer 1

• water is polar molecule
• slightly negatively charged oxygen atoms attract slightly slightly positive hydrogen atoms of other water molecules

Question 2

Explain 5 properties of water that are important in biology

Answer 2

1. Metabolite
   - used in condensation / hydrolysis / photosynthesis / respiration
2. Solvent (can dissolve solutes)
   - allows metabolic reactions to occur
   - allows transport of substances
3. High specific heat capacity
   - buffers changes in temperature
   - as can gain / lose a lot of heat / energy without temperature
   - good habitat for aquatic organisms as temperature more stable than land
   - helps organisms maintain a constant internal body temperature
4. Large latent heat of vaporisation
   - allows effective cooling via evaporation of a small volume
   - so helps organisms maintain a constant internal body temperature
5. Strong cohesion between water molecules
   - supports columns of water in tube - like transport cells of plants
   - produces surface tension what water meets air, supporting small organisms