Question

Assertion: Azolla pinnata is used as a biofertilizer in rice cultivation.
Reason: Azolla performs nitrogen fixation with the help of symbiotic bacterium Bacillus sp.

• A. If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion
• B. If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion
• C. If Assertion is true but the Reason is false
• D. If both Assertion and Reason are false

Answer 1

Answer: (C)

Nitrogen fixing cyanobacteria (blue green alage) form symbiotic association with several plants,e.g. cycad roots, lichens, liverworts, Azolla. Out of these, Azolla - Anabaena association is of great importance to agriculture. Azolla pinnata is a free floating fresh water form which multiplies rapidly, doubling every 5 - 7 days. Anabaena azolla resides in the leaf cavities of the fern. It fixes nitrogen. A part of the fixed nitrogen is excreted in the cavities and becomes available to the fern. The decaying fern plants release the same for utilization of the rice plants. When field is dried at the time of harvesting,the fern functions as the green manure, decomposing and enriching the field for the next crop.