Write the salient features of nitrogen cycle
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the nitrogen fixation is a very easy process whi h takes place between rizobum bacteria and atmosphere.
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The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, assimilation, ammonification, nitrification, and denitrification.
Nitrogen is essential for many processes; it is crucial for any life on Earth. It is a component in all amino acids, as incorporated into proteins, and is present in the bases that make up nucleic acids, such as DNA and RNA. In plants, much of the nitrogen is used in chlorophyll molecules, which are essential for photosynthesis and further growth. Although Earth’s atmosphere is an abundant source of nitrogen, most is relatively unusable by plants.Chemical processing, or natural fixation, are necessary to convert gaseous nitrogen into forms usable by living organisms, which makes nitrogen a crucial component of food production.
The processes of nitrogen cycle are -
1. Nitrogen fixation
Atmospheric nitrogen must be processed, or fixed, to be used by plants. Some fixation occurs in lightning strikes, but most fixation is done by free-living or symbiotic bacteria called rhizobium which lives in the root nodules of some plants which are called legumes. These convert gaseos nitrogen into organic nitrogen which can be taken up by plants from the soil.
2. Assimilation
Plants take nitrogen from the soil, by absorption through their roots in the form of either nitrates or ammonia. All nitrogen obtained by animals can be traced back to the eating of plants at some stage of the food chain.
Plants can absorb nitrate or ammonia from the soil via their root hairs. If nitrate is absorbed, it is first reduced to nitrite and then ammonia. In plants that have a symbiotic relationship with rhizobia, some nitrogen is assimilated in the form of ammonium ions directly from the nodules. Animals, fungi, and other heterotrophic organisms obtain nitrogen by ingestion of amino acids, nucleotides and other small organic molecules.
3. Ammonification
When a plant or animal dies, or an animal expels waste, the initial form of nitrogen is organic. Bacteria, or fungi in some cases, convert the organic nitrogen within the remains back into ammonium , a process called ammonification or mineralization.
4. Nitrification
The conversion of ammonia to nitrate is performed primarily by soil-living bacteria and other nitrifying bacteria. In the primary stage of nitrification, the oxidation of ammonium is performed by bacteria such as theNitrosomonas species, which converts ammonia to nitrites . Other bacterial species, such as the Nitrobacter, are responsible for the oxidation of the nitrites into nitrates. It is important for the ammonia to be converted to nitrates because accumulated nitrites are toxic to plant life.
5. Denitrification
Denitrification is the reduction of nitrates back into the largely inert nitrogen gas , completing the nitrogen cycle. This process is performed by bacterial species such as Pseudomonasand Clostridium in anaerobic conditions.
6. Anaerobic ammonium oxidation
In this biological process, nitrite and ammoniumare converted directly into molecular nitrogen(N2) gas.
 Nitrogen cycle (an image as you wanted)
To view an amimation of the nitrogen cycle ,
Nitrogen is essential for many processes; it is crucial for any life on Earth. It is a component in all amino acids, as incorporated into proteins, and is present in the bases that make up nucleic acids, such as DNA and RNA. In plants, much of the nitrogen is used in chlorophyll molecules, which are essential for photosynthesis and further growth. Although Earth’s atmosphere is an abundant source of nitrogen, most is relatively unusable by plants.Chemical processing, or natural fixation, are necessary to convert gaseous nitrogen into forms usable by living organisms, which makes nitrogen a crucial component of food production.
The processes of nitrogen cycle are -
1. Nitrogen fixation
Atmospheric nitrogen must be processed, or fixed, to be used by plants. Some fixation occurs in lightning strikes, but most fixation is done by free-living or symbiotic bacteria called rhizobium which lives in the root nodules of some plants which are called legumes. These convert gaseos nitrogen into organic nitrogen which can be taken up by plants from the soil.
2. Assimilation
Plants take nitrogen from the soil, by absorption through their roots in the form of either nitrates or ammonia. All nitrogen obtained by animals can be traced back to the eating of plants at some stage of the food chain.
Plants can absorb nitrate or ammonia from the soil via their root hairs. If nitrate is absorbed, it is first reduced to nitrite and then ammonia. In plants that have a symbiotic relationship with rhizobia, some nitrogen is assimilated in the form of ammonium ions directly from the nodules. Animals, fungi, and other heterotrophic organisms obtain nitrogen by ingestion of amino acids, nucleotides and other small organic molecules.
3. Ammonification
When a plant or animal dies, or an animal expels waste, the initial form of nitrogen is organic. Bacteria, or fungi in some cases, convert the organic nitrogen within the remains back into ammonium , a process called ammonification or mineralization.
4. Nitrification
The conversion of ammonia to nitrate is performed primarily by soil-living bacteria and other nitrifying bacteria. In the primary stage of nitrification, the oxidation of ammonium is performed by bacteria such as theNitrosomonas species, which converts ammonia to nitrites . Other bacterial species, such as the Nitrobacter, are responsible for the oxidation of the nitrites into nitrates. It is important for the ammonia to be converted to nitrates because accumulated nitrites are toxic to plant life.
5. Denitrification
Denitrification is the reduction of nitrates back into the largely inert nitrogen gas , completing the nitrogen cycle. This process is performed by bacterial species such as Pseudomonasand Clostridium in anaerobic conditions.
6. Anaerobic ammonium oxidation
In this biological process, nitrite and ammoniumare converted directly into molecular nitrogen(N2) gas.
 Nitrogen cycle (an image as you wanted)
To view an amimation of the nitrogen cycle ,
Anjusha:
thanks a lot
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