Which of following organisms cannot fix nitrogen?
A. Azotobacter
B. Oscillatoria
C. Anabaena
D.

Question

Which of following organisms cannot fix nitrogen? 
A. Azotobacter 
B. Oscillatoria 
C. Anabaena 
D. Volvox 
E. Nostoc 
Choose the correct answer from the options given below:

Professor PC Thomas Classes · Answer

(d) : Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments many of which can fix atmospheric nitrogen, e.g., Anabaena, Nostoc, Oscillatoria, etc. Some bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter), thus enriching the nitrogen content of the soil.