What is the Nitrogen cycle?

Answer 1

Water pollution affects the nitrogen cycle the least. The nitrogen cycle is the cycle of nitrogen as it enters earth, becomes fixed, and leaves earth, back to the atmosphere. The only way that water pollution can affect the nitrogen cycle is if there is too much trash in one area of a body of water, thus clogging the surface and not allowing algae to absorb the nitrogen. It could also clog the surface and not allow denitrifying bacteria in waterlogged soil to release the nitrogen back into the atmosphere.

Answer 2

Plants need nitrogen for their growth.However, they cannot use nitrogen directly from the atmosphere.Some bacteria present in soil and in the roots of certain plants (eg:pea) convert nitrogen into the form that can be used by plants. Lightning can also bring out this conversion. Animals get nitrogen in the form of proteins by eating plants or other plant eating animals.When plants and animals die, nitrogen is released back into the atmosphere. In this way, nitrogen ciculates between the atmosphere, soil and living organisms. This is known as nitrogen cycle.Nitrogen fixationstyle="COLOR: rgb(0,0,0)" class="h2heading h4" name="Conversion_of_N2">Conversion of N2

The conversion of nitrogen (N2) from the atmosphere into a form readily available to plants and hence to animals and humans is an important step in the nitrogen cycle, that determines the supply of this essential nutrient. There are four ways to convert N2 (atmospheric nitrogen gas) into more chemically reactive forms:

1. Biological fixation: some symbiotic bacteria (most often associated with leguminous plants) and some free living bacteria are able to fix nitrogen as organic nitrogen. An example of mutualistic nitrogen fixing bacteria are the Rhizobiumbacteria, which live in legume root nodules. These species are diazotrophs. An example of the free living bacteria is Azotobacter.
2. Industrial Nitrogen fixation : Under great pressure, at a temperature of 600 C, and with the use of a catalyst, atmospheric nitrogen and hydrogen (usually derived from natural gas or petroleum) can be combined to form ammonia (NH3). In the Haber-Bosch process, N2 is converted together with hydrogen gas (H2) into ammonia (NH3) which is used to make fertilizer and explosives.
3. Combustion of fossil fuels : automobile engines and thermal power plants, which release various nitrogen oxides (NOx).
4. Other processes : Additionally, the formation of NO from N2 and O2 due to photons and especially lightning, are important for atmospheric chemistry, but not for terrestrial or aquatic nitrogen turnover.

Assimilation

Plants can absorb nitrate or ammonium ions from the soil via their root hairs. If nitrate is absorbed, it is first reduced to nitrite ions and then ammonium ions for incorporation into amino acids, intense nucleic acids, and chlorophyll.In plants which have a mutualistic relationship with rhizobia, some nitrogen is assimilated in the form of ammonium ions directly from the nodules. Animals, fungi, and other heterotrophic organisms absorb nitrogen as amino acids, nucleotides and other small organic molecules.

Ammonification

When a plant dies, an animal dies, or an animal expels waste, the initial form of nitrogen is organic. Bacteria, or in some cases, fungi, convert the organic nitrogen within the remains back into ammonium(NH4), a process called ammonification or mineralization. Enzymes Involved:

• GS: Gln Synthetase (Cytosolic & PLastid)
• GOGAT: Glu 2-oxoglutarate aminotransferase (Ferredoxin & NADH dependent)
• GDH: Glu Dehydrogenase:
  • Minor Role in ammonium assimilation.
  • Important in amino acid catabolism.

style="COLOR: rgb(0,0,0)" class="h2heading h3" name="Nitrification_">Nitrification

The conversion of ammonia to nitrates is performed primarily by soil living bacteria and other nitrifying bacteria. The primary stage of nitrification, the oxidation of ammonia (NH3) is performed by bacteria such as the Nitrosomonas species, which converts ammonia to nitrites (NO2-). Other bacterial species, such as the Nitrobacter, are responsible for the oxidation of the nitrites into nitrates (NO3-).It is important for the nitrites to be converted to nitrates because accumulated nitrites are toxic to plant life.

Denitrification

Denitrification is the reduction of nitrates back into the largely inert nitrogen gas (N2), completing the nitrogen cycle. This process is performed by bacterial species such as Pseudomonas and Clostridium in anaerobic conditions.They use the nitrate as an electron acceptor in the place of oxygen during respiration. These facultatively anaerobic bacteria can also live in aerobic conditions.

Anaerobic ammonium oxidation

In this biological process, nitrite and ammonium are converted directly into dinitrogen gas. This process makes up a major proportion of dinitrogen conversion in the oceans.

Answer 3

The "nitrogen cycle" is a term used to describe the process by which fish poo is broken down into ammonia as it rots, then that ammonia is digested by bacteria to become nitrites which are slightly less harmfull to marine ecosystems, then those nitrites are broken down into nitrates by another type of bacteria and the cycle is completed. incidentally, the nitrates formed are excellent plant food.

Answer 4

In this system Four process occur ;

i) Formation of Nitrates:

It is the formation of nitrogen into nitrates because nitrogen is not directly available to plants. Formation of nitrates or Nitrogen Fixation occur through :

1. Atmospheric nitrogen fixation ( Through lightening)

2. Biological nitrogen fixation (Through bacteria)

3. Industrial nitrogen fixation (Through industries )

ii) Ammonification & Nitrification:

Formation of nitrites and then nitrates through nitrifying and ammonifying bacteria from dead organic materials.

iii) Assimilation:

It is the assimilation of nitrogen in the form of nitrates by living organisms.

iv) Denitrification:

It is the formation of nitrogen from nitrates through nitrifying bacteria.

Answer 5

provide living things with the necessities of life and do not need people to activate the cycles

Answer 6

N2 is an inert gas and can dissolve in water. It is a mixture. When either the water temperature increases or air pressure decreases, the nitrogen will bubble in the water and escape.