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The Nitrogen Cycle

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The Nitrogen Cycle A2 OCR Biology By the end of this session I will: be able to describe the importance of nitrogen in living systems. outline the role of micro ... – PowerPoint PPT presentation

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Title: The Nitrogen Cycle


1
The Nitrogen Cycle
  • A2 OCR Biology

2
By the end of this session I will
  • be able to describe the importance of nitrogen in
    living systems.
  • outline the role of micro-organisms in the
    cycling of nitrogen
  • Describe the nitrogen cycle using the appropriate
    AS/A2 scientific language.

3
Nitrogen the basics needed for
  • Nitrogen (N) is an element like carbon. All
    creatures need nitrogen to survive.
  • Nitrogen is needed for the synthesis of proteins
    e.g. enzymes.
  • Nitrogen is also an important component of
    nucleic acids

4
Nitrogen the basics chemistry of
  • There are huge amounts of nitrogen gas in the
    atmosphere, but most animals and plants have no
    way of using it as it is very unreactive due to
    the triple covalent bond.
  • It needs to be fixed (put into a biologically
    useful compound). After it is fixed, it can then
    start to move through the cycles and organisms in
    an ecosystem.

5
Nitrogen the basics sources of
  • Let's start with the main sources of nitrogen.
    Nitrogen gas is the most abundant element in our
    atmosphere.
  • The other main source of nitrogen is in the
    nitrates of soil. The nitrogen in the atmosphere
    cannot be used while the nitrates in the soil can
    be used by plants. Nitrogen can be converted into
    useful nitrate compounds by bacteria, algae, and
    even lightning. Once in the soil, the nitrogen
    becomes biologically accessible.

6
Importance of bacteria in the nitrogen cycle
  • Nitrogen fixing bacteria
  • Nitrifying bacteria
  • Denitrifying bacteria

7
Nitrogen fixing bacteria
  • Function.
  • converts nitrogen into nitrogen containing
    compounds
  • E.g. .
  • Rhizobium
  • Found in .
  • .. Roots nodules of leguminous plants and soil

8
Mutualism
9
Nitrifying bacteria
  • Function.
  • .. Convert ammonia in nitrite ions and then into
    nitrite ions.
  • E.g. ..
  • ..Nitrosomonas and Nitrobacter.
  • Found in.
  • .well aerated soils.

10
Denitrifying bacteria
  • Function.
  • . Convert nitrate into nitrogen gas
  • Found in.
  • . Sewage works, compost and wet soils

11
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12
Other ways in which nitrogen can be fixed
  • Lightning
  • Haber process

13
Lightning
  • The electrical energy of lightning causes
    nitrogen gas (N2) to react with oxygen (O2) in
    the atmosphere to produce nitrate ions (NO3-)
    which reach the soil dissolved in precipitation.
  • Recent research suggests the amount of nitrates
    produced by lightning may be as high as 50.

14
Haber process
15
Basic summary of the nitrogen cycle
16
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