Question

Anabaena is associated with Azolla
A) Stem
B) Leaves
C) Roots
D) Flowers

Answer 1

Anabaena is a cyanobacteria and Azolla is a water fern. They both have a symbiotic relationship between them which is beneficial to both of them.

Complete answer:
To answer this question, we must know about the symbiotic relation between Anabaena and Azolla.
Anabaena is nitrogen fixing symbiotic cyanobacteria which is found in shallow water and moist soil. It is a heterocyst.
Azolla is also called the mosquito fern. Anabaena forms a symbiotic relationship where it leaves in the ovoid cavities of the dorsal leaves in the fern and is connected to the external surrounding through pores. The cyanobacterium gets the carbon and other nutrients and fixes nitrogen for the Azolla.
Uses-

The Azolla is used as a biofertilizer in the rice fields.
It is also used as food for fishes and insects.
It is also used in water purification.
It helps in controlling the growth of weeds.

Additional Information: Azolla produces toxic blooms in the environment. The population of Azolla increases rapidly due to sufficient nitrogen. It releases certain cytotoxins which are dangerous for other organisms including humans.

Thus the correct answer is option (B).

Note: Symbiosis is a mutual association between two organisms in which both the organisms are benefited. One organism provides shelter and the other provides essential nutrients. This type of association is seen in the root nodules of leguminous plants which provide shelter to the Rhizobium and the Rhizobium fix nitrogen for the plant.