Vanita M.

Nitrogen fixation is a process by which atmospheric nitrogen gas is converted into organic and inorganic compounds, like ammonia and amino acids.

It occurs through biogeochemical cycles. There are two ways by which it happens. 

1. Physical Nitrogen Fixation through lightning and rainfall.

2. Biological Nitrogen Fixation through bacterias:

In Physical fixation, the atmospheric nitrogen reacts with water present in the air, and due to lightning, it converts into compounds like HNO3 and reaches the earth surface along with rain. In the soil, it dissociates and forms compounds of nitrogen oxide and is absorbed by plants.

3. In biological fixation the atmospheric nitrogen is fixed into nitrites and nitrates by many free-living bacterias and symbiotic bacteria like rhizobium which lives in the roots of leguminous plants like pea plant. These bacteria provide the nitrites and nitrates to the plant, and thus plant uses it to make amino acids which are concerned into proteins in the plant body.

When an animal eats the plant the nitrogen is released back into the soil in urine, also when any animal or plant dies their bodies decompose and release ammonia (NH3) which is converted back into nitrogen (N2) by certain denitrifying bacteria and nitrogen is returned into the atmosphere in its elemental form. This is a complete nitrogen cycle.

For standard 4,5,6,7 students, is the whiteboard mandatory? Please share some tips and tricks for the same.