What is nitrogen metabolism in biology
What is nitrogen metabolism in biology:- Nitrogen is the major and essential mineral element for plants. Nitrogen plays an important of cell. In addition to water it is the second limiting factor for plant growth. Nitrogen has a significant place in plant metabolism.
Nitrogen metabolism is an important process of the life cycle of plant. Two types of phenomena are involved in the metabolism of a substance
Source of nitrogen:-
The main source of nitrogen are atmosphere and soil. It is present in molecular form in atmosphere. Although the major part of atmospheric gas is nitrogen but higher plant cannot use this free molecular nitrogen directly. Therefore soil is the only source of nitrogen for plants where it is found both in inorganic and organic forms.
Forms of nitrogen:-
The nitrogen to be taken by plants may be divided mainly into four types
- Nitrate nitrogen
- Ammonical nitrogen
- organic nitrogen
- Molecular nitrogen
Nitrogen is absorbed by higher plants largely in the form of nitrate ion the natural supply of nitrogen in soil goes on by rain water and by the decomposition of dead bodies of plants and animals Although nitrite ion is also absorbed by plants but nitrate ion is an important source of nitrogen for many plants.
Nitrogen is present as ammonia (NH3) and ammonium ion Ammonia is formed by the physical and chemical fixation of free atmospheric nitrogen and by biological processes. It is also formed by the decomposition of nitrogenous compound by the various types of micro- organism. This ammonia gets mixed up with the soil and is absorbed by the plants.
organic nitrogen is obtained by soil from amino acid amides proteins and other nitrogenous organic compound . These organic compound are obtained from decaying plant and animal bodies through micro organism. Most of the amino acid are not absorbed directly from soil by plant but first of all these amino acids are oxidized into ammonia and organic acid then ammonia is oxidized into nitrate before it is absorbed by plants.
The nitrogen is present in gaseous state in the atmosphere in atmosphere its quantity is approximately 79% but higher plants cannot utilize this nitrogen directly . like carbon dioxide (co2) and oxygen (O2) it is not diffused into plant through stomata. Most of the higher plants absorb nitrogen in fixed form only soil.
The higher plants cannot utilize atmospheric molecular nitrogen . They can absorb it only When it is available in the form of nitrogenous compound such as nitrites, ammonia etc. some lower plant blue green aglac or cyanobacteria and bacteria have the capability to to utilize molecular nitrogen directly.