You are tasked with restoring a degraded ecosystem that has experienced a shortage of nitrogen. Which of the following steps could you take?

• A. Introduce nitrogen-fixing bacteria, which convert nitrogen gas to nitrogen-containing compounds.
• B. Introduce denitrifying bacteria, which convert nitrate to nitrogen gas.
• C. Introduce nitrifying bacteria, which convert nitrate to ammonium.
• D. All of the above.

Answer: (A)

Verified step by step guidance

1. Understand the role of nitrogen in ecosystems: Nitrogen is a crucial element for plant growth and is a major component of amino acids and nucleic acids. In ecosystems, nitrogen is often a limiting factor for productivity.
2. Identify the nitrogen cycle processes: The nitrogen cycle includes several key processes such as nitrogen fixation, nitrification, and denitrification. Each process involves different types of bacteria that transform nitrogen into various forms.
3. Consider nitrogen-fixing bacteria: These bacteria convert atmospheric nitrogen gas (N₂) into ammonia (NH₃) or related compounds, making nitrogen available to plants. This step is essential for increasing nitrogen availability in the ecosystem.
4. Evaluate the role of denitrifying bacteria: These bacteria convert nitrates (NO₃⁻) back into nitrogen gas (N₂), which is released into the atmosphere. This process reduces the amount of nitrogen available in the soil, which may not be ideal for restoring nitrogen levels.
5. Assess the impact of nitrifying bacteria: These bacteria convert ammonia (NH₃) into nitrites (NO₂⁻) and then into nitrates (NO₃⁻), which plants can absorb. Introducing nitrifying bacteria can help increase the availability of nitrogen in a form that plants can use.