Nitrogen cycle

• Bacteria examples

  A) rhizobium

  B) azotobacter

  C) nitrosomonas

  D) nitrobacter

  
• Using nitrogen


  • making proteins and nucleic acids
  • 78% of the atmosphere is nitrogen
  • atmospheric nitrogen is useless - must be converted to a usable form through bacteria
• Key words

  • nitrogen fixation
  • ammonification
  • nitrification
  • denitrification
• Rhizobium


  • have a mutualistic/symbiotic relationship with plants
  • bacteria provides the plant with nitrogenous compounds
  • plant provides the bacteria with carbohydrates
• Animal waste - urine and faeces

  contain nitrogen compounds which are also turned into ammonia by decomposers
• denitrification


  under anaerobic conditions
• Usable nitrogen


  • lightning can fix nitrogen
  • artificial fertilisers provide usable nitrogen to and ecosystem