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Nitrogen The importance of Nitrogen
Organisms require nitrogen for the synthesis of:
- Proteins
- Amino acids
- Nucleic acids
- etc.
Amino Acid structure
However, the form of nitrogen cannot be acquired from the atmosphere in its
original gaseous form. Instead, organisms acquire nitrogen from
photosynthetic plants and organisms.…read more

Slide 3

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Plants actively transport nitrogen in the form of nitrates up
through their roots.
From here, they incorporate them into their macromolecular
structure. This is where consumers will acquire their nitrogen
In natural ecosystems, saprobiotic microorganisms (decomposers)
decompose dead and decaying organisms which restores the nitrate
levels in the soil. However, in artificial ecosystems these levels are
restored using fertilisers.…read more

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Nitrogen Fixation
Conversion of nitrogen gas into nitrogen-containing compounds. Nitrogen-fixing
bacteria = aerobic
This can be achieved industrially or even by lightening. In the nitrogen respiration
cycle however, this is mainly conducted by nitrogen-fixing bacteria.
The two main types of nitrogen-fixing bacteria:
Mutualistic nitrogen-fixing Free-living nitrogen-
bacteria: fixing bacteria:
These bacteria live of plant Live freely in soil and
root nodules and give the convert nitrogen to
plant amino acids in return ammonia which naturally
for carbohydrates. converts to ammonium-
ions in the soil.…read more

Slide 5

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The conversion of ammonium-containing compounds into
Examples of these compounds include; urea,
proteins, vitamins, nucleic acids, animals, plants
Saprobiotic microorganisms feast on these ammonium compounds, releasing ammonia. Some
microorganisms e.g. bacteria secrete enzymes on these compounds which break them down.
Ammonia converts to ammonium ions in the soil ­ this form of
ammonium is needed for nitrification.…read more

Slide 6

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The oxidation of ammonium ions ultimately into nitrate ions.
This process is completed
by nitrifying bacteria.
These bacteria also use
the energy released from
the oxidation reactions.
As nitrifying bacteria respire aerobically they require
Ammonia -> Ammonium ions -> nitrite ions -> nitrate ions oxygen. Thus soil must be kept drained and aerated for
maximum productivity.
The more effectively they can work then the more
nitrates can be formed for plants!…read more

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