Question

steps of nitrogen fixation

Answer 1

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:

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

 

Nitrogen Fixation

Nitrogen fixation is the process by which gaseous nitrogen (N2) is converted to ammonia (NH3 or NH4+) via biological fixation or nitrate (NO3-) through high-energy physical processes. N2 is extremely stable and a great deal of energy is required to break the bonds that join the two N atoms. N2 can be converted directly into NO3- through processes that exert a tremendous amount of heat, pressure, and energy. Such processes include combustion, volcanic action, lightning discharges, and industrial means. However, a greater amount of biologically available nitrogen is naturally generated via the biological conversion of N2 to NH3/ NH4+. A small group of bacteria and cyanobacteria are capable using the enzyme nitrogenase to break the bonds among the molecular nitrogen and combine it with hydrogen.

Answer 2

Nitrogen - nitrogen taken by plants nitrogen present in the atmosphere- bacteria like rhizobuim takes nitrogen from the soil and convert in nitrogenous compound - uptaken by plants both the atmospheric as well as compound nitrogen - animals eat plants - die or animal excreta - nitrogen goes back to soil - change into nitrogen and then send back into atmosphere