Identify the free living nitrogen fixing bacteria
A. Rhizobium
B. Mycorrhiza
C. Azospirillum
D. Azotobacter
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → C and D only
A. Rhizobium — False. Lives in root nodules (symbiotic).
B. Mycorrhiza — False. A fungus–root association.
C. Azospirillum — True.
D. Azotobacter — True.
NCERT Extract:
Microbes as Biofertilisers – “… You have studied about the nodules on the roots of leguminous plants formed by the symbiotic association of Rhizobium. These bacteria fix atmospheric nitrogen into organic forms, which is used by the plant as nutrient. Other bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter), thus enriching the nitrogen content of the soil.”