Mutualistic nitrogen fixing bacteria, otherwise known as bacteria in root
nodules (legumes, peas, beans, lentils and clover) reduce gaseous nitrogen
to ammonia, similarly to the free living nitrogen fixing bacteria.
The bacteria synthesises the nitrogen into amino acids, and
the plant utilieses this. It is mutualistic as both the plant and
the bacteria benefit from this. The bacteria recieves
Free living nitrogen fixing bacteria, otherwise
known as bacteria in the soil, reduce gaseous
nitrogen to ammonia.
Bacteria use ammonia to synthesise amino acids and internalise
The bacteria then dies, and decays, releasing the
nitrogen compounds into the soil.
Plants absorb nitrates from the soil, which are used to
form amino acids (proteins).
Plants are eaten - therefore the amino
acids are absorbed and assimilated into
animals amino acids.
Assimilation - The absorption of nutrients into the
body after digestion in the intestine and its
transformation in biological tissues and fluids.
Both the plant (producer) and animal (consumer) die. Dead
matter/detritus still contain nitrogen still fixed in organic
Decomposers release ammonia into the soil
Nitrifying bacteria oxidise ammonia to nitrites.
Different nitrifying bacteria oxidise nitrites to nitrates.
Plants absorb nitrates from the soil.
Reduces nitrates to nitrogen gas, replenishing the atmosphere.
Problems in waterlogged soil and aquatic conditions,
as the sediment is in anaerobic conditions. The
anaerobic basterica reduces nitrates and ammonium
back to nitrogen using nitrates as oxygen.