Given below are two statements:
Statement I : Nitrogenase enzyme is sensitive to presence of molecular oxygen
Statement II : Nodules contain leghemoglobin which protects nitrogenase enzyme from oxygen
In light of the above statements, choose the correct answer from the options given below:
Statement I : Nitrogenase enzyme is sensitive to presence of molecular oxygen
Statement II : Nodules contain leghemoglobin which protects nitrogenase enzyme from oxygen
In light of the above statements, choose the correct answer from the options given below:
Show Hint
- Both Statement I and Statement II are true
- Both Statement I and Statement II are false
- Statement I is correct but Statement II is false
- Statement II is correct but Statement I is false
The Correct Option is A
Solution and Explanation
Biological nitrogen fixation requires a specialized enzyme complex coupled with oxygen-buffering regulatory mechanisms.
Step 2: Detailed Explanation:
1. Statement I is true: The nitrogenase enzyme complex (comprising Fe-protein and MoFe-protein) is irreversibly denatured and inactivated in the presence of free molecular oxygen ($O_2$).
2. Statement II is true: Legume root nodules synthesize leghemoglobin (an oxygen-binding heme-protein), which acts as an efficient oxygen scavenger to buffer free $O_2$ concentrations to low levels ($pprox 10\,\text{nM}$) while delivering sufficient oxygen flux to bacteroid respiratory chains for ATP synthesis.
Step 3: Final Answer:
Thus, both Statement I and Statement II are true.
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