Biogeochemical Cycles

• The essential biomolecules (CHNOPS) are:

  Carbon

  Hydrogen

  Nitrogen

  Oxygen

  Phosphorus

  Sulfur
• What are the key processes in the Water Cycle?

  • Evaporation
  • Condensation
  • Precipitation
  • Transpiration
  • Runoff
• The Nitrogen Cycle

  • Organisms need nitrogen for the manufacture of proteins and DNA.
• The Nitrogen Cycle has 5 parts to it (two processes, three organisms):

  • Ammonification
  • Nitrification
  • Producers
  • Consumers
  • Decomposers
• First part of the Nitrogen Cycle, Ammonification: bacteria convert nitrogen into ammonia
• Second part of the Nitrogen Cycle, Nitrification: other bacteria convert ammonia into nitrites or nitrates
• Third part of the Nitrogen Cycle: Producers can now absorb the nitrogen from the soil
• Fourth part of the Nitrogen Cycle: Consumers get their nitrogen by the devouring of producers or other consumers.
• Fifth part of the Nitrogen Cycle: Decomposers will break down dead animals and plants into ammonia.
• Eutrophication: The enrichment of a body of water with nutrients, especially nitrogen and phosphorus
• What is nitrogen fixation?


  The process of converting nitrogen from the atmosphere into a form that can be used by plants. (nitrates, nitrites)
• What organism plays a key role in nitrogen fixation?


  Bacteria
• What is assimilation?


  Living organisms integrate the nutrients from various external resources to their body, and use them to satisfy the energy demands required to stay alive.
• What is the relationship between leaching and eutrophication?


  Nutrient runoff from leaching can contribute to eutrophication.