ecosystems Flashcards

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1
Q

what are the 4 steps in the nitrogen cycle

A
  • nitrogen fixation
  • ammonification
  • nitrification
  • denitrification
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2
Q

what is nitrogen fixation

A
  • nitrogen gas in the atmosphere is turned into ammonia by bacteria such as Rhizobium and Azotobacter
  • this ammonia can be used by plants
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3
Q

what is the bacteria Rhizobium and what does it do

A
  • bacteria found inside root nodules (growth on the roots) of leguminous plants
  • they form a relationship with the plants as they provide the plant with nitrogen compounds and the plant provides them with carbohydrates
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4
Q

what is the process of ammonification

A
  • when nitrogen compounds from dead organisms are turned into ammonia by decomposers
  • these go on to form into ammonium ions
  • animal waste also contains nitrogen compounds
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5
Q

what is nitrification

A
  • when ammonium ions in the soil are changed into nitrogen compounds that can be used by plants
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6
Q

what nitrifying bacteria changes ammonium ions into nitrites

A
  • nitrosomonas
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7
Q

what does the bacteria nitrobacter do

A
  • changes nitrites into nitrates
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8
Q

what is denitrification

A
  • when nitrates in the soil are converted into nitrogen gas by denitrifying bacteria
  • use nitrates in the soil to carry out respiration and produce nitrogen gas
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9
Q

what conditions does denitrification happen in

A
  • anaerobic conditions, no oxygen e.g. waterlogged soils
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