Page 4 - 2. Lesson notes- Bio- geo chemical cycles-1

Nitrogen-fixing bacteria play a crucial role in fixing the atmospheric nitrogen into nitrogen

compounds that can be used by the plants.
Steps :-

• The plants absorb the usable nitrogen compounds from the soil through their roots.

Then, these nitrogen compounds are used for the production of proteins and other
compounds in the cell.

• Animals assimilate nitrogen by consuming these plants or other animals that contain
nitrogen. Humans consume proteins from these plants and animals, and then, the nitrogen

assimilates into our system.

• During the final stages of the nitrogen cycle, bacteria and fungi help decompose

organic matter, where the nitrogenous compounds get dissolved into the soil which is again
used by the plants.

• Some bacteria then convert these nitrogenous compounds in the soil and turn it into
nitrogen gas and it goes back to the atmosphere.

These set of processes repeat continuously and thus maintain the percentage of nitrogen in

the atmosphere.