5.4 Nutrient Cycles

• Nutrient cycles ensure the continuous availability of nutrients for living organisms
• Nutrient cycles are vital for ecosystem stability and productivity.


  True
• The carbon cycle involves the movement of carbon dioxide and organic compounds
• The nitrogen cycle includes nitrogen gas, ammonia, and nitrates.


  True
• What is the role of decomposers in nutrient cycles?

  Release nutrients from organic matter
• Atmospheric nitrogen is converted into ammonia by nitrogen-fixing bacteria
• Understanding nutrient cycles is essential for maintaining ecosystem productivity and stability.


  True
• The three main nutrient cycles are carbon, nitrogen, and phosphorus
• Why are nutrient cycles vital for ecosystems?

  Ecosystem stability and productivity
• Photosynthesis is a key process in the carbon cycle where plants use sunlight to convert carbon dioxide into organic compounds.


  True
• Decomposers in the carbon cycle break down organic matter, releasing carbon back into the soil and atmosphere
• Which bacteria convert atmospheric nitrogen into ammonia in nitrogen fixation?

  Nitrogen-fixing bacteria
• In assimilation, plants absorb nitrates from the soil to build proteins and nucleic acids.
• What is released into the atmosphere when fossil fuels are burned?

  Carbon dioxide
• Match the process with its description in the carbon cycle:

  Photosynthesis ↔️ Converts carbon dioxide into organic compounds

  Respiration ↔️ Releases carbon dioxide into the atmosphere

  Decomposition ↔️ Releases carbon into soil and atmosphere

  Combustion ↔️ Releases carbon dioxide by burning organic matter
• Nitrogen fixation is carried out by nitrogen-fixing bacteria, which convert atmospheric nitrogen into ammonia.


  True
• What is the primary process in the carbon cycle that converts carbon dioxide into organic compounds using sunlight?

  Photosynthesis
• Decomposition releases carbon back into the soil and atmosphere.


  True
• Ammonia is converted into nitrites and then nitrates by nitrifying bacteria
• What process releases phosphate ions from rocks into the soil?

  Weathering
• How do animals obtain phosphorus in the phosphorus cycle?

  Consumption
• What is the final step in the phosphorus cycle that carries phosphorus to bodies of water?

  Sedimentation
• Match the human activity with its impact on nutrient cycles:

  Deforestation ↔️ Reduces carbon sequestration

  Fossil fuel combustion ↔️ Releases excess carbon dioxide

  Fertilizer use ↔️ Causes eutrophication
• What are nutrient cycles in ecosystems?

  Natural pathways of nutrients
• Match the nutrient cycle with its key elements:

  Carbon Cycle ↔️ Carbon dioxide, organic compounds

  Nitrogen Cycle ↔️ Nitrogen gas, ammonia, nitrates

  Phosphorus Cycle ↔️ Phosphate ions
• What are the three main nutrient cycles?

  Carbon, nitrogen, phosphorus
• Match the nutrient cycle with its key ecosystem components:

  Carbon Cycle ↔️ Atmosphere, plants, animals, soil

  Nitrogen Cycle ↔️ Soil, plants, microorganisms

  Phosphorus Cycle ↔️ Soil, rocks, plants
• Order the key processes in the carbon cycle:

  1️⃣ Photosynthesis

  2️⃣ Respiration

  3️⃣ Decomposition

  4️⃣ Combustion
• What is the first step in the phosphorus cycle?

  Weathering of rocks
• What are nutrient cycles and what do they ensure in ecosystems?

  Natural pathways for essential elements
• Match the nutrient cycle with its key elements:

  Carbon Cycle ↔️ Carbon dioxide, organic compounds

  Nitrogen Cycle ↔️ Nitrogen gas, ammonia, nitrates

  Phosphorus Cycle ↔️ Phosphate ions
• Nutrient cycles involve the continuous movement of chemical elements through biotic and abiotic components.
• What is the process by which organisms release carbon dioxide into the atmosphere?

  Respiration
• Steps in the nitrogen cycle:

  1️⃣ Nitrogen Fixation

  2️⃣ Nitrification

  3️⃣ Assimilation

  4️⃣ Ammonification

  5️⃣ Denitrification
• What are the two products formed during nitrification in the nitrogen cycle?

  Nitrites and nitrates
• Denitrification converts nitrates back into nitrogen gas, which is then released into the atmosphere.

  True
• In the phosphorus cycle, rocks release phosphate ions into the soil through weathering.
• Match the process with its description in the nitrogen cycle:

  Nitrogen Fixation ↔️ Converts atmospheric nitrogen into ammonia

  Nitrification ↔️ Converts ammonia into nitrites and nitrates

  Assimilation ↔️ Plants absorb nitrates from the soil

  Denitrification ↔️ Converts nitrates back into nitrogen gas
• The phosphorus cycle involves the movement of phosphate ions through soil, rocks, and plants, but not through the atmosphere.

  True
• Organisms release carbon dioxide back into the atmosphere through the process of respiration