Question

Given below are two statements, one is labelled as Assertion (A) and other labelled as Reason (R). 
• [Assertion (A):] Inoculated Azospirillum culture did not show growth in Nitrogen free malate broth incubated at 37 °C under shaking conditions. 
• [Reason (R):] Azospirillum requires microaerophilic conditions for nitrogen fixation. Aerobic conditions inhibit nitrogen fixation. 
In light of the above statements, choose the correct answer from the options given below. 
 

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

The nitrogenase enzyme is universally sensitive to oxygen.
Organisms use different strategies to protect it:
- Azospirillum prefers microaerophilic environments.
- Cyanobacteria use specialized cells called heterocysts.
- Legumes produce oxygen-binding leghemoglobin in their nodules.

Answer 1

The Correct Option is A