Water and its functions
- Water is vital to living organisms
- 80% of cells contents are water
- Water is a reactant in loads of chemical reactions, e.g. photosynthesis and hydrolysis reactions
- Water is a solvent - some substances can dissolve in it. Most biological reactions take place in a solution.
- Water transport substances - as solvent and liquid easily transport all types of materials, e.g. glucose, oxygen around plants and animals.
- Water helps temperature control - carries heat away (when it evaporates) from a surface, which cools the surface and lowers the temperature.
Water molecule structure
- H2O - Two hydrogen atoms and One oxygen atom by shared electrons
- Because shared negative hydrogen electrons are pulled towards oxygen atom, other side of hydrogen atoms is slightly positive charge.
- The unshared negative electrons on the oxygen atom give it a slight positive charge.
- This makes water a POLAR molecule, negative charge on one side and positive charge on the other.
- Negative side of the H2O (Oxygen) attract the positive side of other water molecules (hydrogen).
- This attraction is called hydrogen bonding - gives…