Question

How would you explain the nitrogen cycle?

Answer 1

The cyclic series of natural processes involving the movement of nitrogen and its compounds from air `to` soil `to` organisms `to`air is called nitrogen cycle.

Explanation:

The process by which amount of nitrogen is circulated and recirculated throughout the world of living organism is known as nitrogen cycle.

Diagram:

http://ib.bioninja.com.au/options/option-c-ecology-and-conser/c6-nitrogen-and-phosphorus/nitrogen-cycle.html

Stages:
Following are the principal stages of this cycle:

• Nitrogen Fixation:
  Plants can't utilize atmospheric nitrogen directly. Some plants' nodules have nitrogen fixing bacteria(e.g Rhizobium) which fix the nitrogen in soil air and convert it into amino acids. This process is called nitrogen fixation.
• Ammonification:
  It is breakdown of nitrogenous compounds like amino acids or proteins into ammonia with the help of microorganisms.
• Nitrification:
  Several bacteria oxidize ammonia or ammonium ions into nitrates. This oxidation is known as nitrification.
• Assimilation:
  It is the absorption and utilization of ammonia or nitrates by the plant. The plants can utilize ammonium directly but most of the nitrogen moves from the soil into roots in the form of nitrates. Nitrates are reduced back to ammonium in plant. This assimilation process require energy but once it(energy is provided, it is not required for other assimilations.
• Denitrification:
  The activities of certain soil anaerobic bacteria breakdown the nitrates in the absence of oxygen. Consequently, oxygen and nitrogen are produced. Oxygen is used by anaerobic bacteria for their own respiration while nitrogen is recycled back to the atmosphere.