Question

explain nitrogen cycle

Answer 1

It is the cyclic process by which nitrogen changes from its elemental form present in atmosphere to simple molecules that enter living beings and form complex molecules. These complex molecules are then broken down again to release nitrogen back to atmosphere.
Nitrogen cycle involves following steps -

1) Nitrogen fixation --- Atmospheric nitrogen is converted to water soluble nitrates and nitrites . This is done by nitrogen fixing bacteria like azotobacter, rhizobium..

2) Nitrogen assimilation --- Plants absorb soluble nitrate ion and form amino acids, that are used for making proteins.Animals take organic nitrogen from plants directly or indirectly.

3)Ammonification --- It is the process of ammonia formation by decomposition or breakdown of dead and complex organic matter .This is done by microorganisms living in the soil ...for example -- purifying bacteria.

4) Nitrification --- It is the process of conversion of ammonia into nitrites and then to nitrates by nitrifying bacteria.

5) Denitrification ---- It is the process of reducing nitrates or ammonia present in soil to molecular nitrogen that gets back into atmosphere.This is done by microorganism like Pseudomonas.

Answer 2

Explanation:

Nitrogen cycle is the process by which nitrogen is converted into its various chemical forms and becomes available to living organisms. The nitrogen compounds like protein, nucleic acids are required to all living organisms. Most organisms cannot intake nitrogen in a form it is present in nature.

The processes that participate in this cycle to change the form of nitrogen are

Nitrogen fixation – During lightening or action of some microbes the inert nitrogen breaks down and combines with oxygen in air to form nitrous oxide. This process is called nitrogen fixation.

Nitrification: Some nitrifying bacteria are present in the soil which absorb the atmospheric nitrogen and make it available for the plants to uptake. This is called nitrification.

Decay: By the process of decaying as an action of decomposing microbes, the proteins (compound of nitrogen) present in decaying plant or animal bodies return to the environment.

Denitrification: Some bacteria are present inside the deep layer of soil that break down the nitrate and release nitrogen to the atmosphere. They are denitrifying microorganisms. They release back the nitrogen absorbed by the above processes and end the nitrogen cycle.

 

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