Question

During biological nitrogen fixation in root nodules ratio of protons, electrons and ATP required is

• A. 1:2:1
• B. 1:1:2
• C. 2:1:1
• D. 1:2:3

Hint:

For every 1 molecule of $NH_3$ produced, 8 ATP are required. Since 2 $NH_3$ are formed in the full reaction, 16 ATP are consumed.

Answer 1

The Correct Option is B

Step 1: Reaction of Nitrogen Fixation:
The standard equation for biological nitrogen fixation catalyzed by nitrogenase is: \[ N_2 + 8e^- + 8H^+ + 16ATP \rightarrow 2NH_3 + H_2 + 16ADP + 16P_i \]
Step 2: Determine the Ratio:
We need the ratio of Protons ($H^+$) : Electrons ($e^-$) : ATP. From the equation: \[ 8 H^+ : 8 e^- : 16 ATP \]
Step 3: Simplify the Ratio:
Divide all terms by 8: \[ 1 : 1 : 2 \]
Step 4: Final Answer:
The ratio is 1:1:2, which corresponds to Option (B).