5.4 Nutrient Cycles

• What is the primary role of nutrient cycles in ecosystems?

  Ensuring continuous nutrient availability
• Match the nutrient cycle with its essential nutrient:

  Nitrogen Cycle ↔️ Nitrogen

  Carbon Cycle ↔️ Carbon

  Phosphorus Cycle ↔️ Phosphorus

  Water Cycle ↔️ Water
• Decomposers release ammonia from dead organisms during ammonification.


  True
• Which bacteria converts nitrate into nitrogen gas during denitrification?

  Pseudomonas denitrificans
• Match the stage of the nitrogen cycle with its key process and bacteria involved:

  Nitrogen Fixation ↔️ N₂ → NH₃/NH₄⁺; Azotobacter

  Ammonification ↔️ Organic matter → NH₃/NH₄⁺; Decomposers

  Nitrification ↔️ NH₃/NH₄⁺ → NO₂⁻ → NO₃⁻; Nitrosomonas

  Denitrification ↔️ NO₃⁻ → N₂; Pseudomonas denitrificans
• Weathering of rocks releases phosphates into the soil
• Nutrient cycles involve the movement of nutrients between biotic and abiotic
• The water cycle involves the movement of water among plants, animals, atmosphere, soil, and water bodies.


  True
• Which processes are involved in the water cycle?

  Plants, animals, atmosphere
• During nitrification, ammonia is oxidized into nitrite and then nitrate
• The nitrogen fixation stage requires atmospheric nitrogen and results in the formation of ammonia
• Plants convert carbon dioxide into organic carbon compounds during photosynthesis.


  True
• Combustion of fossil fuels releases stored carbon as CO₂ into the atmosphere.


  True
• What does the carbon cycle describe?

  Flow of carbon
• The nitrogen cycle involves the cycling of nitrogen, which is an essential nutrient for organisms
• What is the role of nitrogen-fixing bacteria in the nitrogen cycle?

  Converting N₂ into NH₃
• Denitrification occurs under anaerobic conditions.
• Denitrification occurs under aerobic conditions.

  False
• Combustion releases carbon dioxide into the atmosphere
• The phosphorus cycle has an atmospheric phase.

  False
• The phosphorus cycle cycles phosphorus among plants, animals, soil, and water
• The phosphorus cycle involves the cycling of phosphorus among plants, animals, soil, and water
• Decomposers release organic nitrogen back into the soil during ammonification.

  True
• The nitrogen cycle ensures the continuous cycling of nitrogen between the atmosphere, soil, and living organisms.


  True
• Match the stage of the nitrogen cycle with its key process:

  Nitrogen Fixation ↔️ Conversion of N₂ into NH₃

  Ammonification ↔️ Release of NH₃ from organic matter

  Nitrification ↔️ Oxidation of NH₃ to NO₃⁻

  Denitrification ↔️ Conversion of NO₃⁻ to N₂
• What role do decomposers play in the carbon cycle?

  Release CO₂ and return carbon
• Stages of the carbon cycle in correct sequence

  1️⃣ Photosynthesis

  2️⃣ Respiration

  3️⃣ Decomposition

  4️⃣ Combustion

  5️⃣ Storage
• Respiration releases CO₂ into the atmosphere.


  True
• Where is carbon stored in the environment?

  Atmosphere, oceans, fossil fuels
• The phosphorus cycle recycles phosphate
• Unlike the carbon cycle, the phosphorus cycle does not have an atmospheric phase
• What do decomposers release in the carbon cycle?

  Carbon dioxide
• Match the human activity with its impact on a nutrient cycle:

  Fertilizer use ↔️ Eutrophication

  Burning fossil fuels ↔️ Climate change

  Mining ↔️ Water pollution
• The nitrogen cycle involves the movement of nitrogen from the atmosphere, soil, and water to plants and animals.


  True
• Arrange the stages of the nitrogen cycle in the correct sequence:

  1️⃣ Nitrogen Fixation

  2️⃣ Ammonification

  3️⃣ Nitrification

  4️⃣ Denitrification
• Which bacteria converts ammonia into nitrite during nitrification?

  Nitrosomonas
• Denitrifying bacteria convert nitrate (NO₃⁻) back into nitrogen gas
• Order the key stages of the carbon cycle:

  1️⃣ Photosynthesis

  2️⃣ Respiration

  3️⃣ Decomposition

  4️⃣ Combustion

  5️⃣ Storage
• Order the steps of the phosphorus cycle:

  1️⃣ Weathering of rocks

  2️⃣ Uptake by plants

  3️⃣ Consumption by consumers

  4️⃣ Decomposition

  5️⃣ Geological uplift
• Match the nutrient cycle with its essential nutrient, biotic, and abiotic components:

  Nitrogen Cycle ↔️ Nitrogen; Plants, animals, decomposers; Atmosphere, soil, water

  Carbon Cycle ↔️ Carbon; Plants, animals, microorganisms; Atmosphere, water, soil