4.1.3 The Nitrogen Cycle

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

  Nitrogen Fixation ↔️ Converts atmospheric nitrogen into ammonia

  Ammonification ↔️ Decomposes organic matter into ammonia

  Nitrification ↔️ Converts ammonia into nitrite and then nitrate

  Denitrification ↔️ Converts nitrate back into atmospheric nitrogen
• The Haber process is an example of biological nitrogen fixation.

  False
• Nitrification increases the availability of nitrate
• Biological nitrogen fixation is carried out by nitrogen-fixing bacteria
• Biological nitrogen fixation is carried out by specialized bacteria such as Rhizobium.


  True
• Nitrification is a two-step process that converts ammonia into nitrate
• Nitrification increases the availability of nitrate for plants.


  True
• The enzyme nitrate reductase converts nitrates into nitrites
• Decomposition releases ammonia through a process called ammonification.


  True
• The nitrogen cycle ensures nitrogen availability for plants and maintains nitrogen balance in ecosystems.


  True
• Match the stage of nitrification with the bacteria involved:

  Ammonia to Nitrite ↔️ Nitrosomonas

  Nitrite to Nitrate ↔️ Nitrobacter
• Nitrate reductase converts nitrates into nitrites.


  True
• Ammonia is incorporated into organic compounds through the enzyme glutamine synthetase
• Match the stage of denitrification with the outcome:

  Nitrate to Nitrite ↔️ NO₃⁻ → NO₂⁻

  Nitrite to Nitric Oxide ↔️ NO₂⁻ → NO

  Nitric Oxide to Nitrous Oxide ↔️ NO → N₂O

  Nitrous Oxide to Nitrogen ↔️ N₂O → N₂
• What is one environmental impact of overuse of fertilizers in agriculture?

  Eutrophication
• The nitrogen cycle is crucial for plant growth and overall ecosystem health
• Nitrogen fixation converts atmospheric nitrogen into ammonia.


  True
• What is the product of nitrogen fixation that plants can use for growth?

  Ammonia
• Which two types of bacteria are involved in nitrification?

  Nitrosomonas and Nitrobacter
• Denitrification reduces the amount of nitrogen available in the soil.


  True
• The Haber process requires high temperature and pressure.


  True
• The Haber process, used in industrial nitrogen fixation, reacts nitrogen gas with hydrogen
• Nitrosomonas bacteria convert ammonia into nitrite during nitrification.

  True
• Assimilation of nitrates involves incorporating nitrates into organic compounds such as proteins
• Nitrite reductase converts nitrites into ammonia during nitrate assimilation.


  True
• Main stages of the nitrogen cycle in the correct sequence

  1️⃣ Nitrogen Fixation

  2️⃣ Ammonification

  3️⃣ Nitrification

  4️⃣ Denitrification
• Why is nitrification crucial for plants?

  Nutrient availability
• Assimilation of nitrates involves their incorporation into organic compounds such as proteins
• Steps in nitrate assimilation by plants

  1️⃣ Nitrate Uptake

  2️⃣ Nitrate Reduction

  3️⃣ Nitrite Reduction

  4️⃣ Ammonia Assimilation
• What is the outcome of ammonification?

  Release of ammonia
• The nitrogen cycle is essential for ecosystem health.

  True
• Sustainable management of nitrogen resources is crucial for mitigating environmental issues.


  True
• Stages of the nitrogen cycle in the correct order

  1️⃣ Nitrogen Fixation

  2️⃣ Ammonification

  3️⃣ Nitrification

  4️⃣ Denitrification
• Nitrosomonas and Nitrobacter are examples of nitrifying bacteria
• Rhizobium bacteria live in the root nodules of legumes
• Order the steps of nitrification

  1️⃣ Ammonia is converted into nitrite

  2️⃣ Nitrite is converted into nitrate
• Match the stage of the nitrogen cycle with its process and organisms involved:

  Nitrogen Fixation ↔️ Converts atmospheric nitrogen into ammonia, Rhizobium

  Ammonification ↔️ Breaks down organic matter into ammonia, Decomposers

  Nitrification ↔️ Converts NH₃ into NO₂⁻ and then NO₃⁻, Nitrosomonas, Nitrobacter

  Denitrification ↔️ Converts NO₃⁻ back to N₂, Denitrifying bacteria
• Nitrogen fixation is the process of converting atmospheric nitrogen into ammonia
• Industrial nitrogen fixation is a natural process that requires high energy input.

  False
• Nitrobacter bacteria convert nitrite into nitrate