The nitrogen cycle - created from Mind Map

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Nitrogen fixation

Ammonification/decomposition

Nitrification

Denitrification

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.

Free living nitrogen fixing bacteria, otherwise known as bacteria in the soil, reduce gaseous nitrogen to ammonia.

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 carbohydrates.

Bacteria use ammonia to synthesise amino acids and internalise them.

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.

Both the plant (producer) and animal (consumer) die. Dead matter/detritus still contain nitrogen still fixed in organic molecules.

Assimilation - The absorption of nutrients into the body after digestion in the intestine and its transformation in biological tissues and fluids.

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.