Question

If the nitrogenase enzyme has been inactivated by radiation, there will be no

• A. fixation of atmospheric nitrogen
• B. fixation of nitrogen by microorganisms
• C. conversion of nitrite to nitrate
• D. conversion of ammonia into nitrite

Answer 1

The correct option is B fixation of nitrogen by microorganisms

Conversion of atmospheric nitrogen into ammonia or other nitrogenous compounds like nitrates is called nitrogen fixation. There are several ways of nitrogen fixation like electrical nitrogen fixation, industrial nitrogen fixation and biological nitrogen fixation. Reduction of nitrogen into ammonia by microorganisms is called biological nitrogen fixation. This reaction is catalysed by the enzyme nitrogenase. Nitrogenase is a Mo-Fe protein present exclusively in some prokaryotes. Hence, if nitrogenase enzyme is inactivated there will be no biological nitrogen fixation but other ways of nitrogen fixation can occur.
Oxidation of ammonia to nitrite and later oxidation of nitrite to nitrate is carried out by microorganisms and that does not require nitrogenase enzyme.