Nitrogen Cycle

Which gas is present in abundance in the atmosphere? No doubt it is Nitrogen, which is one of the most important elements used for the synthesis of proteins required for body building and also one of the most important constituents of nucleic acids.

It is not possible to absorb free N2 directly from the atmosphere by the plants unlike the direct absorption of CO2 and O2. The atmospheric nitrogen is converted into its absorbable form as nitrates. This process is called nitrogen fixation.

Go through Illustration IV and study different ways through which N2 is converted in to nitrates. In addition to this, use of chemical fertilizers also increases the nitrate content in the soil.

 

Plants absorb the soil nitrates and use it for the biosynthesis of protein. This protein is transferred through the food chains. Observe the diagrammatic representation Vand study the N2 cycle.

 

 

· Prepare a table showing the types of bacteria involved in the N2-cycle and their various roles.

· Prepare a brief note after detailed discussion of the question how nitrate absorbed by the plants returns to the atmosphere.

You have realized the role of N2-cycle in maintaining the constancy of atmospheric nitrogen content.