Science 9 - Nitrogen Cycle - PowerPoint PPT Presentation

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Science 9 - Nitrogen Cycle

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Introduction to the nitrogen cycle – PowerPoint PPT presentation

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Title: Science 9 - Nitrogen Cycle


1
the NitrogenCycle
2
Nitrogen Cycle?
  • A nutrient cycle in which nitrogen atoms are
    circulated through the living and non-living
    environment
  • Problem
  • 79 of atmosphere made of nitrogen (N2)
  • Living things cant use nitrogen directly

3
Getting Nitrogen
  • Organisms cant get nitrogen directly, so get it
    in a usable form called nitrates

Nitrogen (N2) (in atmosphere)
Nitrates(NO3)-
4
Getting Nitrogen
  • Examples
  • Heterotrophs animals obtain nitrogen stored in
    the food they eat
  • Autotrophs plants obtain nitrogen in the form of
    nitrates from soil

5
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6
Why is Nitrogen Important?
  • Nitrogen atoms are an important part of
  • Proteins building material of
    living things.
  • Example muscles are made of protein

7
Lawn with little nitrogen
8
Lawn with adequate nitrogen
9
Fertilizer source of nitrogen
10
Fertilizer source of nitrogen
11
Protein in hemoglobin (Blood)
12
Protein in muscles
13
Protein in hair
14
Protein in Fingernails
15
Why is Nitrogen Important?
  • DNA molecule in body which contains
    hereditary information (instructions for
    life)

16
Steps of the Nitrogen Cycle
17
Overview
  • Nitrogen cycle
  • Nitrogen Fixation Obtaining nitrogen from air,
    to be used by living things
  • Denitrification Returning nitrogen back into the
    air

18
Nitrogen Fixation
  • Nitrogen Fixation is conversion of nitrogen from
    atmosphere into nitrates to be used by plants
  • Nitrogen Nitrates
  • ?
  • Nitrogen Fixation occurs in two ways 1)
    lightning and 2) nitrogen fixing bacteria

19
1) Lightning
  • Energy from converts nitrogen and oxygen in the
    air into nitrates.
  • Energy Nitrogen Oxygen ? Nitrates

20
1) Lightning (cont)
  • Rain carries nitrates down into soil
  • Plants absorb nitrates and water through their
    roots
  • Note nitrates contain nitrogen!

21
1) Lightning (cont)
  • Plants stored nitrogen in their bodies
  • Nitrogen is passed through the food webs in the
    food we eat.

22
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24
2) Nitrogen Fixing Bacteria
  • Bacteria in the soil convert nitrogen into
    nitrates.
  • Why?
  • Bacteria get food (sugar) from plants
  • Bacteria release nitrates into soil which plants
    absorb

25
2) Nitrogen Fixing Bacteria (nodules)
26
2) Nitrogen Fixing Bacteria
  • NOTE not all plants have nitrogen fixing
    bacteria, only legumes (clover, pea, alfalfa).

27
2) Nitrogen Fixing Bacteria
  • QUESTION How would clovers growing on your front
    lawn benefit the grass?

28
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29
Denitrification
  • The opposite of nitrogen fixation
  • Bacteria convert nitrates into nitrogen
  • Completes nitrogen cycle, ensures a balance of
    nitrates in soil and nitrogen in atmosphere

30
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31
Decomposers
  • When an animal dies, its body contains nitrogen
    (obtained from the food eaten)
  • Decomposers help release this nitrogen back into
    the nitrogen cycle

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36
INTERFERING WITH THE NITROGEN CYCLE
37
SUBSISTENCE FARMING
  • Natural farming. Farming to the natural
    tolerance of the soil.
  • Advantage does not overuse the soil, no
    fertilizers, eco-friendly
  • Disadvantage small amounts of food

38
SUBSISTENCE FARMING
39
COMMERCIAL FARMING
  • This is large scale farming, in which fields are
    overplanted
  • Crop plants use up naturally occurring nitrates
    in the soil

40
ONTARIOs GREEN BELT
41
NIAGRA the Fruit belt
42
  • Problem
  • Crops planted yearly, using up all nitrogen in
    soil
  • Nitrogen needs to be replaced

43
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44
Commercial farming
  • Replace nitrogen by placing
  • Chemical Fertilizers or Natural Fertilizers
    (manure) directly into the soil

45
Algal bloom
  • Fertilizers washed out by rain into streams and
    rivers
  • Extra nitrogen stimulates growth of water plants
  • Plants use up all oxygen in the water

46
Algal bloom
  • Plants use up all oxygen in the water
  • Kills all life in the pond

47
Algal bloom
48
Algal Bloom
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