Question

Select the correct order of steps involved in Nitrogen fixation by microbes:
A. Nitrification
B. Denitrification
C. Organic nitrogen degradation
D. Ammonification
E. Nitrite- formation

• A. C, E, D, B, A
• B. C, A, B, E, D
• C. C, D, E, A, B
• D. C, B, A, D, E

Hint:

Nitrogen Cycle Steps:
Organic Nitrogen (C) $\xrightarrow{\text{Ammonification}}$ $\text{NH}_4^+$ (D) $\xrightarrow{\text{Nitrosomos}}$ $\text{NO}_2^-$ (E) $\xrightarrow{\text{Nitrification}}$ $\text{NO}_3^-$ (A) $\xrightarrow{\text{Denitrification}}$ $\text{N}_2$ (B).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the correct functiol order of microbial steps converting organic nitrogen compounds back into atmospheric dinitrogen in the global nitrogen cycle.

Step 2: Key Formula or Approach:
Trace nitrogen transformation through microbial decomposition and oxidative/reductive pathways: Organic N (C) $\rightarrow{}$ Ammonia (D) $\rightarrow{}$ Nitrite (E) $\rightarrow{}$ Nitrate (A) $\rightarrow{}$ Nitrogen Gas (B)

Step 3: Detailed Explation:

• 1. Organic Nitrogen Degradation (C): Decomposers break down proteins and nucleic acids from dead plant/animal matter into simpler nitrogenous wastes.

• 2. Ammonification (D): Ammonifying bacteria convert nitrogenous organic wastes into ammonia ($\text{NH}_3$) and ammonium ions ($\text{NH}_4^+$).

• 3. Nitrite Formation (E): Nitrosifying bacteria (e.g., Nitrosomos) oxidize ammonium ions into nitrites ($\text{NO}_2^-$).

• 4. Nitrification (A): Nitrifying bacteria (e.g., Nitrobacter) further oxidize nitrites ($\text{NO}_2^-$) into nitrates ($\text{NO}_3^-$).

• 5. Denitrification (B): Denitrifying bacteria (e.g., Pseudomos) reduce soil nitrates back into gaseous nitrogen ($\text{N}_2$), completing the cycle.

Step 4: Fil Answer:
The correct order of nitrogen cycle transformations is C, D, E, A, B.