Question

Which of the following microorganism is involved in nitrogen fixation?

• A. Rhizobium
• B. Aspergillus
• C. Chlamydomonas
• D. Spirogyra

Answer 1

The correct option is (A):

Explanation of the correct option:

1. ​Rhizobium is a bacteria present as a symbiotic association in the root nodules of the leguminous plants.
   
2. The nitrogen fixed by the bacteria is utilized by the plant and in turn, Rhizobium receives nourishment from the plant.
   

Explanation of the incorrect options:

Option (B):

1. Aspergillus is not a nitrogen fixing bacteria.
   

Option (C):

1. Chlamydomonas is a type of green algae which is found in the aquatic habitats.

Option (D):

1. ​Spirogyra is an algae that grows in the aquatic habitat.
   

Final Answer: Rhizobium is involved in nitrogen fixation.