Question

Match bacteria/microbes with their functions:

List I	List II
A. Achromobacter --- III. Denitrification B. Nitrobacter --- IV. Nitrite to Nitrate C. Clostridium --- I. N2 fixation D. Nitrosomonas --- II. Ammonia to Nitrite conversion	III. Denitrification IV. Nitrite to Nitrate I. N2 fixation II. Ammonia to Nitrite conversion

• A. A-I, B-II, C-III, D-IV
• B. A-IV, B-III, C-II, D-I
• C. A-III, B-IV, C-I, D-II
• D. A-I, B-III, C-II, D-IV

Hint:

Nitrosomonas: NH$_3$ $\rightarrow$ NO$_2^-$; Nitrobacter: NO$_2^-$ $\rightarrow$ NO$_3^-$; Clostridium: N$_2$ fixation; Achromobacter: denitrification.

Answer 1

The Correct Option is C

Step 1: Concept
Microbial functions in the nitrogen cycle.

Step 2: Meaning
Different bacteria catalyse different steps of the nitrogen cycle.

Step 3: Analysis
Achromobacter (A): Involved in denitrification (NO$_3^-$ $\rightarrow$ N$_2$) --- matches III.
Nitrobacter (B): Oxidises NO$_2^-$ to NO$_3^-$ --- matches IV.
Clostridium (C): Anaerobic nitrogen fixer (N$_2$ $\rightarrow$ NH$_3$) --- matches I.
Nitrosomonas (D): Oxidises NH$_4^+$ to NO$_2^-$ --- matches II.

Step 4: Conclusion
Correct matching: A-III, B-IV, C-I, D-II. Final Answer: (C)