Nitrogen cycle

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Nitrogen forms of the gases of the atmosphere.

Nitrogen from the atmosphere is converted to ammonium (NH4+) compounds by

Nitrogen (N2 ) is converted to nitrous oxide (NO) by

Denitrifying bacteria

 

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The above diagram outlines the pathways atmospheric nitrogen is cycled through the biosphere. Nitrogen exists in animals mainly in the form of proteins. Amino acids are not stored and are broken down to form urea when not used to make protein. Occasionally, during starvation, protein is used as an energy source but only after the amine group from the amino acids are removed. The amino group is combined with carbon dioxide to form urea((NH2)2CO).
Legumes provide a source of soluble nitrogen compounds able to be used by plants. Often legumes are planted in fields during winter to increase the nitrogen content of the soil without having to use artificial fertilizers.

Exercises

Eutrophication

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