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Topic: Nitrogen cycle

Related Topics

Nitrogen fixation

Nitrogen

Nitrification

Denitrification

Biogeochemical cycle

Soil life

Oxygen cycle

Mycorrhiza

Cycle

Rhizobia

Eutrophication

Nitrogenase

Ammonia

Nitrate

CNO cycle

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	nitrogen cycle
		Nitrogen, in the form of inorganic compounds (such as nitrates) in the soil, is absorbed by plants and turned into organic compounds (such as proteins) in plant tissue.
		A proportion of this nitrogen is eaten by herbivores, with some of this in turn being passed on to the carnivores, which feed on the herbivores.
		The nitrogen is ultimately returned to the soil as excrement and when organisms die, and is converted back to inorganic forms by decomposers.
	www.tiscali.co.uk /reference/encyclopaedia/hutchinson/m0008077.html (311 words)

	Nitrogen Cycle (Site not responding. Last check: 2007-11-03)
		Two nitrogen oxides are found in the air as a result of interactions with oxygen.
		Nitrogen will only react with oxygen in the presence of high temperatures and pressures found near lightning bolts and in combustion reactions in power plants or internal combustion engines.
		Nitrogen in the air becomes a part of biological matter mostly through the actions of bacteria and algae in a process known as nitrogen fixation.
	www.elmhurst.edu /~chm/onlcourse/chm110/outlines/nitrogencycle.html (345 words)

	Nitrogen Cycle (Site not responding. Last check: 2007-11-03)
		Nitrogen cycle in reef aquaria refers to the process by which biological waste by-products are converted from toxic substances to harmless compounds through the actions of bacteria.
		Nitrogen: In a properly setup reef tank, the nitrates can be further processed by special types of bacteria which convert the nitrates into harmless nitrogen gases which escape into the atmosphere.
		When the process includes this step, the nitrogen cycle is completed and the tank will maintain zero nitrates without significant water changes or the requirement for specialized external equipment to remove it from the system.
	www.reefcorner.com /Manual/nitrogen_cycle.htm (1708 words)

	nitrogen cycle. The Columbia Encyclopedia, Sixth Edition. 2001-05
		Nitrogen is vital to all living matter, both plant and animal; it is an essential constituent of amino acids, which form proteins of nucleic acids, and of many other organic materials.
		Although the earth’s atmosphere is 78% nitrogen, free gaseous nitrogen cannot be utilized by animals or by higher plants.
		But the great bulk of nitrogen fixation is performed by soil bacteria of two kinds: those that live free in the soil and those that live enclosed in nodules in the roots of certain leguminous plants (e.g., alfalfa, peas, beans, clover, soybeans, and peanuts).
	www.bartleby.com /65/ni/nitrocyc.html (711 words)

	Nitrogen cycle - Wikipedia, the free encyclopedia
		The nitrogen cycle is the biogeochemical cycle that describes the transformations of nitrogen and nitrogen-containing compounds in nature.
		Nitrogen is essential for many biological processes; it is in all amino acids, is incorporated into proteins, and is present in the bases that make up nucleic acids, such as DNA and RNA.
		As of 2006, the application of nitrogen fertilizer is being increasingly controlled in Britain and the United States.
	en.wikipedia.org /wiki/Nitrogen_cycle (1640 words)

	The Environmental Literacy Council - Nitrogen Cycle
		Nitrogen is both the most abundant element in the atmosphere and, as a building block of proteins and nucleic acids such as DNA, a crucially important component of all biological life.
		Once in the soils and surface waters, nitrogen undergoes a set of changes: its two nitrogen atoms separate and combine with hydrogen to form ammonia (NH This is done by microorganisms that fall into three broad categories: bacteria living in symbiotic relationships with certain plants, free anaerobic bacteria, and algae.
		Nitrogen compounds in various forms, such as nitrate, nitrite, ammonia, and ammonium are taken up from soils by plants which are then used in the formation of plant and animal proteins.
	www.enviroliteracy.org /article.php/479.html (739 words)

	EPA-MAIA - Nitrogen (Site not responding. Last check: 2007-11-03)
		Nitrogen makes up approximately 78% of air (by weight) and is the second most abundant element in the human body.
		Nitrogen is an essential nutrient for life and is naturally cycled through the land, water, and air.
		Nitrogen compounds are also emitted into the air by cars, trucks, electric utilities, and industry where they can be deposited on land or directly into water bodies.
	www.epa.gov /maia/html/nitrogen.html (1750 words)

	Nitrogen Metabolism and the Urea Cycle
		This class of reactions funnels nitrogen from all free amino acids into a small number of compounds; then, either they are oxidatively deaminated, producing ammonia, or their amine groups are converted to urea by the urea cycle.
		Glutamate formed in the course of nitrogen elimination is either oxidatively deaminated by liver glutamate dehydrogenase, forming ammonia, or converted to glutamine by glutamine synthase and transported to kidney tubule cells.
		In subsequent reactions of the urea cycle a new urea residue is built on the ornithine, regenerating arginine and perpetuating the cycle.
	web.indstate.edu /thcme/mwking/nitrogen-metabolism.html (4152 words)

	Nitrogen Cycle
		The nitrogen cycle is defined as the pathways for which nitrogen is recycled.
		As the term suggests, the nitrogen cycle is an unremitting succession of pathways for nitrogen.
		The nitrogen cycle is the continuous recycling of nitrogen as an essential building block for life.
	www.reefscapes.net /articles/articles/2002/nitrogencycle.html (1679 words)

	Nitrogen cycle (Site not responding. Last check: 2007-11-03)
		Nitrogen is essential for biogical processes; for example it is included all amino acids (the stem amin derives from ammonia) is incorporated into proteins and is present in the four that make up nucleic acids such as DNA.
		Plants get nitrogen from the soil by absorption at their roots in the form of either nitrate ions (NO) or ammonia (NH Ammonia is produced in the soil nitrogen fixing organisms such as Azobacter vinelandii which produces the enzyme nitrogenase.
		This is the reverse nitrification and results in nitrates being converted nitrogen gas and lost to the atmosphere.
	www.freeglossary.com /Nitrogen_cycle (554 words)

	The Nitrogen Cycle
		The nitrogen cycle involves some basic concepts of biology and chemistry, but is a very important component in understanding the aquarium environment.
		When an organism dies, nitrogen is moved from plant or animal into the inorganic chemical ammonia by the process of bacterial decay.
		Nitrogen is a necessary component of the aquarium system, and does fairly well in accumulation.
	www.versaquatics.com /nitrogencycle.htm (332 words)

	Nitrogen cycle
		The importance of bacteria in the cycle is inmediately recognized as being a key element in the cycle, providing different forms of nitrogen compounds assimilable by higher organisms.
		Nitrogen is essential for many biological processes; it is in all amino acids, is incorporated into proteins, and is present in the four bases that make up nucleic acids, such as DNA.
		All nitrogen obtained by animals can be traced to the eating of plants at some stage of the food chain.
	www.mrsci.com /Metabolism/Nitrogen_cycle.php (608 words)

	NCAR, UCAR, UOP News Center - Nitrogen Backgrounder
		Nitrogen is essential to all living systems, which makes the nitrogen cycle one of Earth's most important nutrient cycles.
		During electrical storms, large amounts of nitrogen are oxidized and united with water to produce an acid that falls to Earth in rainfall and deposits nitrates in the soil.
		Holland's research focuses on the regional and global nitrogen cycles and their interactions with the carbon and water cycles, including how land ecosystems are affected by air pollution and climate change.
	www.ucar.edu /news/backgrounders/nitrogen.shtml (965 words)

	9(s) The Nitrogen Cycle
		Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins, and nucleic acids.
		Decomposers, found in the upper soil layer, chemically modify the nitrogen found in organic matter from ammonia (NH to ammonium salts (NH This process is known as mineralization and it is carried out by a variety of bacteria, actinomycetes, and fungi.
		Nitrogen in the form of ammonium can be absorbed onto the surfaces of clay particles in the soil.
	www.physicalgeography.net /fundamentals/9s.html (661 words)

	s9chap2 (Site not responding. Last check: 2007-11-03)
		Once the nodule is established, the differentiated bacteria (they become non-motile bacteroids) living in the infected plant cells, reduce atmospheric nitrogen to ammonia which is excreted to the plant cell and is, in turn, assimilated to organic nitrogen (proteins and amino acids) by the plant.
		Nitrogen fixation research will undoubtedly make important contributions to agriculture by substituting traditional fertilizer N inputs (which are costly, polluting and time consuming), with a cheap natural biological alternative.
		Besides the knowledge of the molecular basis of biological nitrogen fixation and the technology to manipulate the genome, a deep understanding of the ecology of nitrogen fixing organisms and of the fate of introduced new genetic information into the soil will be necessary to achieve these goals.
	www.soils.agri.umn.edu /academics/classes/soil2125/doc/s9chap2.htm (1973 words)

	Environmental Biology Sequence - Ecosystems
		The nitrogen cycle is one of the most difficult of the cycles to learn, simply because there are so many important forms of nitrogen, and because organisms are responsible for each of the interconversions.
		The phosphorous cycle is the simplest of the cycles that we will examine (I like to save the simplest for the last sometimes; it's like a cool-down period after a long run).
		This cycle will occur over and over until at last the phosphorous is lost at the bottom of the deepest parts of the ocean, where it becomes part of the sedimentary rocks forming there.
	www.marietta.edu /~biol/102/ecosystem.html (5677 words)

	Science Program > Issues in Ecology > (Site not responding. Last check: 2007-11-03)
		In many ecosystems on land and sea, the supply of nitrogen is a key factor controlling the nature and diversity of plant life, the population dynamics of both grazing animals and their predators, and vital ecological processes such as plant productivity and the cycling of carbon and soil minerals.
		Thanks to the fertilizer effects of nitrogen in stimulating plant growth, this deposition may be acting to influence the atmosphere indirectly by altering the global carbon cycle.
		The nitrogen increases in these rivers are highly correlated with human-generated inputs of nitrogen to their watersheds, and these inputs are dominated by fertilizers and atmospheric deposition.
	www.esa.org /science/Issues/TextIssues/issue1.php (6529 words)

	Geography4Kids.com: BGC Cycles: Nitrogen Cycle
		There are huge amounts of nitrogen gas in the atmosphere, but most animals and plants have no way of using it.
		The nitrogen in the atmosphere cannot be used while the nitrates in the soil can be used by plants.
		Nitrogen atoms are returned to the soil in poop and dead organisms.
	www.geography4kids.com /files/cycles_nitrogen.html (292 words)

	The Nitrogen Cycle
		Nitrogen is the major component of earth's atmosphere.
		These types of bacteria form a symbiotic relationship with legumes--these types of plants are very useful because the nitrogen fixation enriches the soil and acts as a 'natural' fertilizer.
		The use of inorganic fertilizers and depleting nitrogen resources by overharvesting legumes (which have nodules in their roots formed by a symbiotic bacteria that fix nitrogen) and overmining nitrogen also alter an ecosystem.
	library.thinkquest.org /11353/nitrogen.htm (387 words)

	nitrogen cycle (Site not responding. Last check: 2007-11-03)
		The nitrogen cycle is the process by which atmospheric nitrogen is converted to ammonia or nitrates.
		Nitrogen is removed from the atmosphere by lightening and nitrogen fixing bacteria.
		During electrical storms, large amounts of nitrogen are oxidized and united with water to produce an acid which is carried to the earth in rain producing nitrates.
	www.cst.cmich.edu /centers/mwrc/nitrogen.htm (181 words)

	Nitrogen fixation (Site not responding. Last check: 2007-11-03)
		We shall deal first with the process of nitrogen fixation and the nitrogen-fixing organisms, then consider the microbial processes involved in the cycling of nitrogen in the biosphere.
		The total biological nitrogen fixation is estimated to be twice as much as the total nitrogen fixation by non-biological processes.
		So, the only nitrogen available to support new growth will be that which is supplied by nitrogen fixation from the atmosphere (pathway 6 in the diagram) or by the release of ammonium or simple organic nitrogen compounds through the decomposition of organic matter (pathway 2).
	helios.bto.ed.ac.uk /bto/microbes/nitrogen.htm (2449 words)

	The Nitrogen Cycle - Article at The Age of Aquariums - Tropical Fish
		Nitrogen (N) is a chemical element that goes into the composition of two very important classes of organic molecules: proteins and nucleic acids.
		This is the most important part of the Nitrogen Cycle in terms of fishkeeping, but actually it doesn't stop here.
		Now that we know how the Nitrogen Cycle works, we may better understand how to proceed in a new aquarium, to ensure a healthy environment for our fish.
	www.aquahobby.com /articles/e_ciclo.php (1146 words)

	Carolina Biological: Carolina Tips: Nitrate in Ecosystems and Drinking Water (page 1 of 3)
		Marine and estuarine ecologists weighed in next, demonstrating the role of nitrogen in the overproduction of algae and the changes in algal species in coastal and bay waters "enriched" with nitrogen.
		The nitrogen cycle is based on natural events in which atmospheric nitrogen is fixed into compounds, largely as ammonium and nitrate, which are essential mineral nutrients for the growth, repair, and reproduction of plants and algae.
		Then it is converted back to atmospheric nitrogen by denitrifying bacteria that live in anaerobic (oxygen-free) mud, or it is returned to the soil as a mineral nutrient by decomposers (Fig.1).
	www.carolina.com /tips/98oct/tips1098a.asp (491 words)

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