Question

There is a symbiotic alga in the secretory cells of the hydra. It is
A.Nostoc
B.Anabaena
C.Zoochlorellae
D.All of these

Answer 1

Hint: 1.Algae are photosynthetic organisms that have not differentiated body like higher plants. These can be unicellular or multicellular or colonial. These can be also found as parasites or as symbiotic associations with other organisms.
2.In a symbiotic association, both organisms are benefited. Some algae form a symbiotic association with animals.

Complete answer: 1.Hydra is a member of class hydrozoa and phylum Coelenterata. It is found in freshwater.
2.The body of a hydra is made of two walls that are ectoderm and endoderm. Between these two walls a thin, soft, transparent, and non-cellular mesogloea is found.
3.In mesogloea, a proteinaceous matrix is filled. In the inner gastrodermis layer, myoepithelial cells are found.
4.A species of hydra ‘Hydra Viridissima’ is also called green hydra because of its green color. In its myoepithelial cells, green algae Chlorella Vulgaris is found in symbiotic association. This is an example of endosymbiosis.
5.This alga provides green color to the hydra. All the algae that live with aquatic invertebrates as an endosymbiotic association is called Zoochlorellae.
So the correct option is C. Zoochlorellae.

Note: 1.Coelenterates are lower non chordates. These are aquatic animals and tissue level organization is found in these. Special nematocyst cells are found this is their specific feature and that’s why these are also called cnidarians. It helps to catch prey.
2.Gastro vascular cavity and coelenteron cavity is found in these animals.