The Phosphorus Cycle

• Why is it important that phosphorus gets recycled?

  It is an important biological element in ATP, phospholipids and nucleic acids.
• What does phosphorus mainly exist as?

  Phosphate ions (PO4^3-).
• What are phosphate ions in the form of?

  Sedimentary rock deposits in the sea.
• How do phosphate ions from sedimentary rock become available for plants to absorb?

  The rock is brought to the surface by the geological uplifting of rocks, then weathering and erosion dissolve the phosphate ions
• How are the phosphate ions passed to animals from plants?

  The animals feed off the phosphorus-containing plants.
• What do fungi and bacteria do after the death of the plants and animals?

  They break the organisms down to release the phosphate ions into the soil or water.
• Where do some parts of phosphate ions remain?

  In parts of the organism that are hard to break down, such as bones and shells.
• What happens to the waste material at the end of the phosphorus cycle?

  It is transported by streams and rivers into lakes and oceans where they reform sedimentary rocks.
• What is mycorrhizae?


  A type of fungi that act like extensions of the plant's root system.
• What does mycorrhizae do?

  Increases the total surface area for absorption of water and minerals.
• What are the benefits of mycorrhizae?

  It can resist a drought, and take up inorganic ions more readily.
• How do mycorrhizae fungi play a role in nutrient cycles?

  They improve the uptake of relatively scarce ions such as phosphate ions.
• How is the relationship between plants and mycorrhizae a mutualistic one?

  Plants take in more inorganic ions, whilst the fungus receives organic compounds from the plant such as sugars and amino acids.