Nitrogen Cycle And Methanogenesis

Question 1

What is nitrogen fixation, and why is it important?

Answer 1

Nitrogen fixation is the process of converting atmospheric nitrogen (N₂) into ammonia (NH₃), which plants can use. It’s essential because most organisms can’t use nitrogen in its atmospheric form.

Question 2

What is denitrification, and why is it ecologically significant?

Answer 2

Denitrification is the reduction of nitrates (NO₃⁻) or nitrites (NO₂⁻) back to nitrogen gas (N₂), removing nitrogen from the ecosystem. This is important as too much nitrogen can harm plant and bacterial health.

Question 3

What organisms perform methanogenesis, and in what type of environments does it occur?

Answer 3

Methanogenesis is performed by methanogens, which are strict anaerobes, typically archaea. It occurs in anaerobic environments like wetlands, digestive tracts, and hydrothermal vents.

Question 4

Explain the main pathways of methanogenesis.

Answer 4

Methanogenesis has two main pathways:
1. CO₂ is reduced with H₂ to produce methane (CH₄) and water.
2. Acetate is split into methane (CH₄) and CO₂.

Question 5

Why is methanogenesis important for the carbon cycle?

Answer 5

Methanogenesis plays a critical role in the carbon cycle by converting carbon compounds into methane, a greenhouse gas, which impacts atmospheric carbon levels and global climate.

Question 6

How do nitrifying bacteria contribute to nitrogen cycling?

Answer 6

Nitrifying bacteria, like ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), convert ammonia to nitrate, making nitrogen available to plants and contributing to soil fertility.

Question 7

What are the main pathways of methanogenesis?

Answer 7

The main pathways are:
1. CO₂ Reduction Pathway: Carbon dioxide (CO₂) is reduced with hydrogen (H₂) to produce methane (CH₄) and water (H₂O).
2. Acetoclastic Pathway: Acetate (CH₃COOH) is split into methane (CH₄) and carbon dioxide (CO₂).