WATER

It is a liquid compound made up of two part7s of hydrogen and one part of oxygen. It usually forms about 70% to 90% part of cytoplasm and 45% to 80% part of the whole body. It does yield energy, but it is vital in the maintenance of life.

Structure

The water molecule, H2O is formed by the combination of two hydrogen atoms and one oxygen. The molecule behaves as dipole, as oxygen atom shares two electrons with each of two hydrogen atoms. One end of water molecule is slightly positive and the other slightly negative. The electronegative oxygen atoms tend to attract the single electron of the hydrogen atom. Several water molecules tend to get attracted t each other, forming a Lattice Structure. These bonds are not strong and are called hydrogen bonds.

Biological function of water

        i.            i) Water act as a best solvent: it is the medium in which soluble materials are dissolved.

      ii.            ii) Water as a reagent: there are some reactions in the body which are ionic in nature and ionization takes place    in water.

    iii.            iii) Water as a temperature stabilizer: it means large amount of heat can be lost with minimum loss of water. It causes elimination of excess heat by evaporation of sweat which gives a cooling effect.

     iv.            iv) Water as a high surface tension: Due to high surface tension and cohesion, conduction of water through xylem vessels in the plants is possible.

       v.            v) It is the medium of transport of some substances in the body like foods.