Question

Explain nitrogen cycle step by step

Answer 1

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Nitrogen is essential to life because it is a key component of proteins and nucleic acids. Nitrogen occurs in many forms and is continuously cycled among these forms by a variety of bacteria. Although nitrogen is abundant in the atmosphere as diatomic nitrogen gas (N2), it is extremely stable, and conversion to other forms requires a great deal of energy. Historically, the biologically available forms NO3- and NH3 have often been limited; however, current anthropogenic processes, such as fertilizer production, have greatly increased the availability of nitrogen to living organisms. The cycling of nitrogen among its many forms is a complex process that involves numerous types of bacteria and environmental conditions.

In general, the nitrogen cycle has five steps:

1)Nitrogen fixation (N2 to NH3/ NH4+ or NO3-)
2)Nitrification (NH3 to NO3-)
3)Assimilation (Incorporation of NH3 and NO3- into biological tissues)
4)Ammonification (organic nitrogen compounds to NH3)
5)Denitrification(NO3- to N2)

Answer 2

The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among the atmosphere, terrestrial, and marine ecosystem.
Conversion of nitrogen into nitrates and nitrites through atmospheric, industrial and biological processes is called as nitrogen fixation. Atmospheric nitrogen must be processed, or "fixed", in a usable form to be taken up by plants.
but most fixation is done by free-living or symbiotic bacteria known as diazotrophs. These bacteria have the nitrogenase enzyme that combines gaseous nitrogen with hydrogen to produce ammonia, which is converted by the bacteria into other organic compounds. Most biological nitrogen fixation occurs by the activity of Mo-nitrogenase, found in a wide variety of bacteria and some Archaea.
Plants can absorb nitrate or ammonium from the soil via their root hairs. If nitrate is absorbed, it is first reduced to nitrite ions and then ammonium ions
When a plant or animal dies or an animal expels waste, the initial form of nitrogen is organic. Bacteria or fungi convert the organic nitrogen within the remains back into ammonium (NH+
4), a process called ammonification or mineralizationThe conversion of ammonium to nitrate is performed primarily by soil-living bacteria and other nitrifying bacteria. In the primary stage of nitrification, the oxidation of ammonium (NH+
4) is performed by bacteria such as the Nitrosomonas species, which converts ammonia to nitrites (NO−
2). Other bacterial species such as Nitrobacter, are responsible for the oxidation of the nitrites (NO−
2) into nitrates (NO−
3).[5] It is important for the ammonia (NH
3) to be converted to nitrates or nitrites because ammonia gas is toxic to plants.
Denitrification is the reduction of nitrates back into nitrogen gas (N2), completing the nitrogen cycle. This process is performed by bacterial species such as Pseudomonas and Clostridium in anaerobic conditions.