Question

Which one of the following can fix nitrogen?

• A. Mycoplasm
• B. Azotobacter
• C. Anabaena
• D. Both B and C

Answer 1

The correct option is D Both B and C

The atmospheric nitrogen is not available to plants. There are some nitrogen fixing bacteria which converts atmospheric nitrogen into ammonia which is readily available to plants. Azotobacter are free-living nitrogen fixing bacteria. Anabaena is a free-living nitrogen fixing bacteria. However, it also forms symbiotic association with plants like mosquito fern. Hence, they are symbiotic bacteria as well.

Thus, the correct answer is 'Both B and C.'