Phosphorus cycle

Cards (18)

  • Phosphate ions are released from rocks on land by chemical weathering and washed into soils by rain
  • Phosphate ions are absorbed by plant roots by active transport
  • Primary consumers feed on plants and the biological molecules in their food are digested into smaller phosphate containing molecules such as nucleotides
  • Nucleotides and phosphate ions are absorbed in the small intestine of primary consumers and used to make nucleic acids and ATP
  • When organisms produce faeces or die, the phosphorus containing substances in their tissues or faeces are digested by saprobiotic bacteria, releasing phosphate ions, which can then be taken up by plants
  • Some phosphate ions are washed from soils into streams, and eventually reach lakes or the sea
  • Phosphate ions in water may be taken up by algae near the surface and incorporated into their biological molecules
  • Algae with phosphorus containing compounds may be eaten by fish, passing the phosphorus along the trophic level
  • When aquatic organisms die they tend to sink to the bottom of lakes or the sea, where they decompose and phosphate ions become trapped in aquatic sediments
  • Over long geological time periods, aquatic sediments form sedimentary rocks and may eventually become exposed back on land, where chemical weathering releases phosphate back into the soil
  • Plants would be incapable of accessing phosphate ions without the help of mycorrhizae
  • Phosphorus is present in a number of vital biological molecules, such as ATP and phospholipids
  • Phosphorus does not exist as a lone element in nature. Instead it naturally exists combined with other elements. Therefore, to obtain phosphorus, organisms take it up as phosphate
  • Saprobionts break down the waste of plants and animals
  • Phosphate originates from rocks
  • Not all the phosphates in the soil are absorbed by plants. Some dissolve in water and are washed to bodies of water
  • Phosphate sinks to the bottom of water and over thousands of years can form rock
  • Phosphorus is important for:
    • creation of nucleotides for DNA and RNA required for protein synthesis
    • making phospholipids required for membrane integrity in cells
    • making NADP and RuBP required for carbon fixation