Water is the main of living
beings and is necessary practically for
biochemical reactions, including as
of photosynthesis. Many
properties water are very important
life.

Carbon is the chemical element of
organic ; carbon dioxide is
also of photosynthesis and
product the energetic metabolism of
beings.

Nitrogen is a chemical
element of amino , the building
blocks of that in their turn
the main functional molecules living
beings; nitrogen is part of the
nucleic molecules, the basis of
, heredity and protein
synthesis.