require nitrogen to produce amino acids. Nitrogen
makes up seventy-eight percent of the atmosphere, but
most organisms can not use this form of nitrogen, and must have
the fixed form. The nitrogen cycle produces the fixed form of
nitrogen these organisms need.
1: A special type of bacteria called nitrogen fixing bacteria
take in atmospheric nitrogen and produce ammonia
Step 2: Other
bacteria use this ammonia to produce nitrates and nitrites, which
are nitrogen and oxygen containing compounds.
Step 3: The
nitrates and nitrites are used by plants to make amino acids which
are then used to make plant proteins.
Step 4: Plants
are consumed by other organisms which use the plant amino acids
to make their own.
Step 5: Decomposers
convert the nitrogen found in other organisms into ammonia and return
it to the soil. A few of these type of bacteria return nitrogen
to the atmosphere by a process called denitrification, however this
amount is small.