4.10) Nitrogen Cycle

4.10 Describe the stages in the nitrogen cycle, including the roles of nitrogen fixing bacteria, nitrifying bacteria and denitrifying bacteria (specific name of bacteria not required.)

N2 - 78.324% called atmosphere

unreactive, abundant

Plants can take in nitrogen in the form of nitrate NO3- to manufacture amino acids which combine together to form protein.

Nitrogen is also important for the formation of DNA.

How do plants get nitrate?

Lightning can combine atmosphere nitrogen with oxygen to form nitrate because it has sufficient energy for the bonding. 

N2 + 3O2 ---> 2NO3-

Use of nitrogen in plant

Plants can take in nitrate from soil or from the atmosphere.

The amino acid contains of carbon, hydrogen, oxygen, and nitrogen (CHON).

The amino acids are then built into protein.

Food chain

Producer ---> Primary consumer ----> Secondary consumer ---> .....

Nitrogen passes through the trophic level in feeding in the form of protein.

Excretion

Animal ---> nitrogen excretion, usually in the form of urea

Urea + H2O ---> Urine

This adds nitrogen back into soil.

Dead

Dead ---> decomposers

Urine/ Urea + Decaying organic molecule ---> breaks down by decomposers into ammonia (NH3)

Ammonia is converted into nitrite

NH3 (ammonia) -----convertion-----> NO2= (nitrite)

with the help of nitrifying bacteria

Plants (root system)

In the soil there's a type of free living bacteria which takes atmospheric (in the air or soil) nitrogen and turns it into nitrate. 

Leguminous plants such as Beans and clover have structure on the roots called nodules. 

nitrate ---> nitrate

Denitrifying bacteria

Presented in the soil

Take nitrate and convert it back to nitrogen.