Question

Denitrification reduces nitrate to nitrogen gas under

• A. Aerobic conditions
• B. Strictly aerobic only
• C. Anoxic conditions with organic carbon
• D. High oxygen only

Hint:

Denitrification: \[ \boxed{ NO_3^- \rightarrow NO_2^- \rightarrow NO \rightarrow N_2O \rightarrow N_2 } \] Occurs under \[ \boxed{\text{Anoxic conditions + Organic carbon}} \]

Answer 1

The Correct Option is C

Step 1: Define denitrification.
Denitrification is a microbial process that reduces nitrate step by step until it is released as nitrogen gas.
Step 2: Identify the conditions the bacteria need.
These bacteria are facultative anaerobes, so they only switch to using nitrate as an electron acceptor when oxygen is absent, and they also need an organic carbon source to supply electrons.
Step 3: Put the requirements together.
Both conditions, oxygen free surroundings and available organic carbon, must be present at once for denitrification to proceed, ruling out the aerobic options.
\[ \boxed{\text{Anoxic conditions with organic carbon}} \]