Question

Select the odd one from the following.

• A. Anabaena
• B. Nostoc
• C. Oscillatoria
• D. Rhizobium

Answer 1

Answer: (D)

Rhizobium is a Gram-negative bacteria that fix atmospheric nitrogen in the leguminous plants.
Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments many of which can fix atmospheric nitrogen, e.g. Anabaena, Nostoc, Oscillatoria, etc. In paddy fields, cyanobacteria serve as an important biofertilizer. Blue-green algae also add organic matter to the soil and increase its fertility.