9.2.2 Nitrogen Cycle

• What is the Nitrogen Cycle?

  Cyclic movement of nitrogen
• What percentage of the Earth's atmosphere is nitrogen gas?

  78%
• Nitrogen fixation is performed by specialized nitrogen-fixing bacteria.

  True
• Nitrates produced during nitrogen fixation can be absorbed by plants.


  True
• What is the end product of nitrogen fixation that plants can absorb?

  Nitrates
• The nitrification process converts ammonia into nitrites and then nitrates
• Match the source of nitrogen with its description:

  Atmospheric nitrogen gas ↔️ Nitrogen gas makes up 78% of the Earth's atmosphere

  Nitrogen fixation ↔️ Conversion of atmospheric nitrogen into ammonia

  Animal waste and decomposition ↔️ Release of nitrogen from organic matter
• Steps in the nitrogen fixation process

  1️⃣ Nitrogen-fixing bacteria break the triple bond in N₂

  2️⃣ Nitrogen is combined with hydrogen to produce NH₃

  3️⃣ Ammonia is converted into nitrites

  4️⃣ Nitrites are converted into nitrates

  5️⃣ Nitrates are absorbed by plant roots
• The nitrification process converts ammonia into nitrites and then nitrates
• Nitrogen fixation converts atmospheric nitrogen gas into forms like ammonia
• Match the step in nitrogen fixation with its product:

  Break Triple Bond ↔️ N

  Ammonia Production ↔️ Ammonia (NH₃)

  Conversion to Nitrites and Nitrates ↔️ Nitrites (NO₂⁻) and Nitrates (NO₃⁻)

  Plant Absorption ↔️ Plant Proteins
• Nitrobacter bacteria convert nitrites into nitrates.


  True
• Match the nitrogen compound with its assimilation by plants:

  Ammonia (NH₃) ↔️ Directly absorbed by roots

  Nitrites (NO₂⁻) ↔️ Converted to nitrates first

  Nitrates (NO₃⁻) ↔️ Readily absorbed by roots
• Steps in the nitrogen cycle

  1️⃣ Nitrogen Fixation

  2️⃣ Nitrification

  3️⃣ Denitrification
• Which enzyme is used by nitrogen-fixing bacteria to convert N₂ into NH₃?

  Nitrogenase
• Steps involved in the nitrogen fixation process

  1️⃣ Nitrogen uptake

  2️⃣ Enzymatic conversion

  3️⃣ Ammonia incorporation
• Nitrates produced during nitrification are readily absorbed by plants.


  True
• The assimilation of nitrogen compounds allows plants to build proteins and nucleic acids.


  True
• Steps involved in the denitrification process

  1️⃣ Nitrate reduction

  2️⃣ Nitrite reduction

  3️⃣ Nitric oxide reduction

  4️⃣ Nitrous oxide reduction
• Steps in the nitrogen fixation process

  1️⃣ Break the triple bond in N₂

  2️⃣ Ammonia production

  3️⃣ Conversion to nitrites and nitrates

  4️⃣ Plant absorption
• Which bacteria converts ammonia into nitrites during nitrification?

  Nitrosomonas
• What is the role of nitrogen in plant growth?

  Essential nutrient
• The nitrogen cycle involves the cyclic movement of nitrogen
• Atmospheric nitrogen gas makes up about 78% of the Earth's atmosphere
• Nitrogenase is the enzyme used by bacteria to convert nitrogen gas into ammonia.


  True
• Match the bacteria with their role in nitrification:

  Nitrosomonas ↔️ Converts ammonia to nitrites

  Nitrobacter ↔️ Converts nitrites to nitrates
• Match the nitrogen compound with its assimilation by plants:

  Ammonia ↔️ Directly absorbed by roots

  Nitrites ↔️ Converted to nitrates first

  Nitrates ↔️ Readily used for synthesis
• The ammonia produced during ammonification can be used in nitrification.


  True
• The Nitrogen Cycle allows nitrogen to continuously cycle between the atmosphere, soil, and living organisms.


  True
• Nitrogen fixation is the conversion of atmospheric nitrogen gas into ammonia and nitrates
• What compound is produced when nitrogen gas combines with hydrogen during nitrogen fixation?

  Ammonia
• Match the source of nitrogen with its description:

  Atmospheric nitrogen gas ↔️ Nitrogen gas makes up 78% of the Earth's atmosphere

  Nitrogen fixation ↔️ Conversion of atmospheric nitrogen into ammonia

  Animal waste and decomposition ↔️ Release of nitrogen from organic matter

  Fertilizers ↔️ Synthetic compounds containing nitrogen
• Nitrogen-fixing bacteria use enzymes to break the triple bond in N₂.

  True
• Nitrification is a two-step process where ammonia is converted into nitrates
• Assimilation is the process by which plants incorporate nitrogen compounds into their tissues
• Ammonification converts organic nitrogen into ammonia by microorganisms.


  True
• What is the primary source of nitrogen in the atmosphere?

  Atmospheric nitrogen gas
• Nitrogen fixation is the conversion of atmospheric nitrogen gas into usable forms such as ammonia and nitrates
• What is the end product of the nitrification process?

  Nitrates
• Nitrogen is a key component of proteins, nucleic acids, and other biomolecules, making it essential for plant growth