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

Name 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

what is the importance of water’s property: Metabolite

used in condensation / hydrolysis / photosynthesis / respiration

what is the importance of water’s property: solvent

allows metabolic reaction to occur (faster in solution)

allows transport of substances e.g. nitrates in xylem, urea in blood

what is the importance of water’s property: high specific heat capacity

buffers changes in temperature

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

good habitat for aquatic organisms as temperature is more stable than on land

helps organisms maintain a constant internal temperature

what is the importance of water’s property: High latent heat of vaporisation

allows effective cooling via evaporation of a small volume e.g. sweat

so helps organisms maintain a constant internal body temperature

what is the importance of water’s property: strong cohesion between water molecules

supports columns of water e.g. transpiration stream through xylem in plants

produces surface tension, supporting small organisms to walk on water