Nitrogen cycle

• Amino acids, proteins, chlorophyll, enzymes, nitrogenous bases are formed from nitrogen in plants.
• Nitrogen is an important element for plant life & is required for synthesis of amino acids, proteins, enzymes, chlorophyll, nucleic acids etc.
• This plays basic role in metabolism, growth, reproduction & transmission of heritable characters. Molecular nitrogen constitutes about 78% of the earth atmosphere but chemically it is inert & cannot be utilized by most living organisms, plants, animals & most organisms so depend on combined nitrogen such as ammonia, nitrates & organic nitrogen compounds.
• The sequence of changes from free atmospheric nitrogen to fixed inorganic nitrogen, simple organic compounds to complex organic compounds in the tissues of plants, animals & microbes. And eventual release of this nitrogen back to the atmosphere is called as Nitrogen cycle.