Cycles

• What is phosphorus used for in organisms?

  It is essential for DNA, RNA, and ATP
• Why is the phosphorus cycle important?

  It is crucial for essential biological molecules
• How does the phosphorus cycle differ from the carbon and nitrogen cycles?

  Phosphorus does not exist as a gas
• Where is phosphorus mainly stored in the environment?

  In rocks as phosphate ions
• What are mycorrhizae?

  Fungi associated with plant roots
• How do mycorrhizae benefit plants?

  They increase surface area for water absorption
• What do plants provide to mycorrhizae in return?

  Carbohydrates from photosynthesis
• What are the main stages of the phosphorus cycle?

  1. Absorption of phosphate ions by plants
  2. Incorporation into biological molecules
  3. Excretion and decomposition
  4. Erosion and sedimentation
  5. Formation of phosphate ions in rocks
• How do plants absorb phosphate ions?

  Through active transport mechanisms
• What happens to phosphate ions after animals digest plant material?

  They are incorporated into biological molecules
• What is guano?

  Excrement from birds rich in phosphorus
• How does guano contribute to the phosphorus cycle?

  It releases phosphate ions into the environment
• What role does sedimentation play in the phosphorus cycle?

  It helps form rocks containing phosphate ions
• What happens to phosphate ions in rocks over time?

  They can be eroded and released back
• How can fertilizers affect the phosphorus cycle?

  They can lead to runoff into oceans
• What is the main source of phosphate ions in the phosphorus cycle?

  Mineral form in rocks
• Why are plants with mycorrhizal associations more drought resistant?

  They can absorb and hold more water
• How does the mutualistic relationship between plants and mycorrhizae work?

  Both provide advantages to each other
• What are the key processes in the phosphorus cycle?

  • Absorption by plants
  • Incorporation into biological molecules
  • Excretion and decomposition
  • Erosion and sedimentation
  • Formation of phosphate in rocks
• Why is the nitrogen cycle important?

  It helps convert nitrogen gas for plants and animals
• Why can't animals and plants obtain nitrogen through gas exchange?

  Nitrogen gas has a triple bond, making it inert
• What role do microorganisms play in the nitrogen cycle?

  They break nitrogen gas bonds to convert it
• How do plants absorb nitrogen-containing substances?

  Through active transport in the roots
• Which biological molecules contain nitrogen?

  Proteins, amino acids, ATP, nucleic acids
• What are the four key processes of the nitrogen cycle?

  • Ammonification
  • Nitrification
  • Nitrogen-fixing
  • Denitrification
• What is ammonification in the nitrogen cycle?

  It is the creation of ammonium from organic matter
• What is nitrification?

  It is the conversion of ammonium to nitrates
• How does nitrogen-fixing occur in plants?

  Through bacteria in root nodules of legumes
• Which plants have root nodules for nitrogen-fixing?

  Leguminous plants
• What is the role of nitrogen-fixing bacteria in soil?

  They convert nitrogen gas into ammonium
• What happens to ammonium during nitrification?

  It is converted to nitrites and then nitrates
• What is the significance of nitrifying bacteria in the soil?

  They convert ammonium to nitrites and nitrates
• How do plants assimilate nitrates?

  By active transport through their roots
• How do animals obtain nitrogen from plants?

  By eating and digesting plant material
• What happens to nitrogen in animal waste and dead organisms?

  It is converted back into nitrogen-containing compounds
• What is the role of decomposers in the nitrogen cycle?

  They break down proteins into nitrogen compounds
• What is denitrification?

  It is the conversion of nitrates back to nitrogen gas
• Why is denitrification undesirable in agriculture?

  It leads to loss of nitrogen from soil
• Under what conditions does denitrification occur?

  When there is insufficient oxygen in the soil
• What is the oxidation process in nitrification?

  Ammonium to nitrite to nitrate is oxidation