Which one of the following can utilize molecular nitrogen (N2) as nutrient for growth ? (A) Rhizobium (B) Spirogyra (C) Mucor (D) Methanococcus.ecplain why not a) explain with reasons.. no link...

Dear student

Please refer the solution below for the said query



There are certain studies which say that some species of Rhizobium and Methanococcus can utilise molecular nitrogen (N2) as source of nitrogen provided in medium for their growth. 

However, as per your level and syllabus, the answer is as under:


Rhizobium can fix atmospheric molecular nitrogen (N₂) and convert it into ammonia in association with leguminous plants. The nitrifying bacteria convert ammonia into nitrates. They cannot utilise molecular nitrogen (N₂) or its converted from directly as nutrient for their own growth. Instead they get carbohydrates, amino acids from plants for survival.

However, it has been observed that methanogens utilise the ammonia produced by thse nitrogen fixing bacteria (say Rhizobium) as nitrogen source for their growth.
Hence, most appropriate option here will be D.


Hope this information clears your doubt about the topic.

Regards