Download The Nitrogen Cycle with Qs

The Nitrogen cycle for Chemistry and Biology.
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Nitrogen in the air
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Nitrogen Fixation by
Symbiotic Bacteria
Absorbed
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Death & Decay
Plant protein
Nitrates NO3Eaten
oxidation
Death & Decay
Nitrities
NO2-
Nitrification
Ammonia NH3
Animal Protein
Excretion
Fill in the missing terms in the
next slide.
The Nitrogen cycle for Chemistry and Biology.
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Nitrogen in the air
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Nitrogen Fixation by
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Absorbed
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Death & Decay
Eaten
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Death & Decay
Nitrification
Excretion
What is Nitrogen Fixation?
• Nitrogen fixation involves
Nitrogen, which is a relatively
inert gas, which is plentiful in air,
being made to combine
chemically with other elements to
form more reactive nitrogen
compounds such as ammonia,
nitrates, or nitrites.
The Chemistry of nitrogen fixation
during electrical storms.
Firstly, nitrogen and oxygen combine
together forming nitrogen monoxide.
Lightning provides the energy.
N 2 + O2
Lightning
2NO
Then the unstable nitrogen monoxide combines
with atmospheric oxygen to form nitrogen dioxide.
NO + 1/2 O2
NO2
The Chemistry of nitrogen fixation
during electrical storms.
The nitrogen dioxide formed now combines
with water in the atmosphere to form nitric
acid.
3NO2
+
H2O Æ
2HNO3
+
NO
Finally, the nitric acid is washed down with the rain into the soil
where it forms nitrates (NO3-) which can be absorbed by plants.
The Role of Bacteria in the
Nitrogen cycle.
Ammonia (NH3) changing to nitrities (NO2-) and then to
nitrates(NO3-) is called nitrification and is done using
chemosynthetic bacteria.
Nitrogen fixing bacteria live in the soil. They convert
atmospheric nitrogen into nitrates in the soil that can then be
absorbed by plant roots. These again are chemosynthetic.
Nitrogen fixing bacteria live in nodules in the roots of bean, pea
lupin and clover plants. They take atmospheric nitrogen and
make available to the plants to make protein. These are
symbiotic and chemosynthetic.
The Role of Bacteria in the
Nitrogen cycle.
• Saprophytic bacteria change dead and
decaying animals and plants into
ammonia(NH3)
Denitrifying bacteria convert soil nitrates to
atmospheric nitrogen. These bacteria are
also chemosynthetic.
What have you learned?
1.What kind of bacteria live in nodules in the roots
of pea and bean plants?.......................................
2.How does plant protein become animal protein?
…………………….
3. What is the conversion of ammonia to nitrities or
nitrities to nitrates called? …………………………..
4.The extraction of nitrogen from the air to make
nitrates in the soil during thunder and lightning is
called ……………… ……………………..
5. Give one other example of nitrogen
fixation from the nitrogen cycle?................
6. Give an example of where chemosynthetic
bacteria function in the nitrogen cycle…………
7. Give an example of where saprophytic
bacteria function in the nitrogen cycle. ………….
8. Other than death and decay, how may animal
protein be recycled in the nitrogen cycle?