Decomposers in the Nitrogen Cycle

Steps:

• Identify the nitrogen cycle stage: decomposition breaks down dead organisms and waste to release ammonium.
• Recall key microorganisms: decomposers convert organic nitrogen into inorganic forms usable by plants.
• List roles: bacteria (e.g., Bacillus) and fungi (e.g., saprophytic molds) perform this breakdown via enzymes.
• Exclude non-decomposers: viruses replicate inside hosts but do not decompose organic matter.

Why A is correct:

• Bacteria and fungi are defined as saprotrophs that enzymatically decompose organic nitrogen compounds, as per ecological roles in nutrient cycling.

Why the others are wrong:

• B: Viruses lack metabolic machinery to decompose; they only parasitize cells.
• C: Excludes bacteria, which are primary decomposers alongside fungi.
• D: Includes viruses, which play no role in decomposition.

Final answer: A