Question

Coralloid roots of Cycas possess a symbiotic Algae. It is
A)Aulosira
B)Spirogyra
C)Ulothrix
D)Anabaena

Answer 1

Hint: The coralloid root is observed in the Cycas. It is developed in clusters at the base of the stem and comes out over the ground. It is dichotomously branched and observed as greenish-brown in a colour. It is made up of the algal zone in the cortex. The plant takes many years to grow, sexual reproduction takes place after 10 years of independent vegetative growth.

Complete answer:
The coralloid roots are mainly present in the Cycas which constitute the symbiotic cyanobacteria. These organisms play a role in the fixation of nitrogen with the help of nitrogenase. The nitrogen fixation gives rise to beneficial amino acids such as asparagine and the citrulline for the growth of the plant. The cyanobacteria that are located inside the coralloid roots of Cycas are chemoheterotrophic and specifically adapted to symbiosis.

Now let us find solution from given options:
A)Aulosira : it is a genus of cyanobacteria. It is found in moist soil. It lives in symbiotic association with the roots of hornworts.
B)Spirogyra : it is a filamentous algae. It belongs to green algae. It lives in symbiotes associated with roots of fungi.
C)Ulothrix : Ulothrix is a non-branched and filamentous algae. It lives in symbiotic association with fungi.
D)Anabaena : cyanobacteria live in symbiosis, only a few species and one of the species is Anabaena. It shows a symbiotic relationship with Cycas.

Hence, the correct answer is option (D)

Note: The coralloid roots of Cycas are the harbour blue-green algae such as the Nostoc, Anabaena, etc. and are not the VAM (vesicular-arbuscular mycorrhiza) which results in a symbiotic association with the fungus. Cycas species are threatened worldwide and almost all the species of Cycas are listed in IUCN Red List.