A marine cartilaginous fish that can produce electric current is 

  • Pristis

  • Torpedo

  • Trygon 

  • Trygon 


B.

Torpedo

Torpedo is a marine cartilaginous fish which produces 8-220 volt electric charge (current) depending on species. Their electric organs are modified lateral muscle plates innervatted by carnrial nerves.

Trygon (sting ray) resembles electric ray in many aspects but is devoid of electricity discharging (or producing) organs. 

Scoliodon (dog fish) is known for its great sense of smell. Pristis or common saw fish (also known as carpenters shark) is charactesised by a long, narrow, flattened rostrum lined with sharp transverse teeth to resembles a saw.

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Select the taxon mentioned that represents both marine and freshwater species

  • Echinoderms

  • Ctenophora

  • Cephalochordata

  • Cephalochordata


D.

Cephalochordata

Cnidarian members are found both in fresh water and marine environments, while members of Ctenophora, Cephalochordata and Echinodermata are found exclusively in the marine environment.

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Planaria possess high capacity of 

  • metamorphosis

  • regeneration

  • alternation of generation

  • alternation of generation


B.

regeneration

Planaria are the type of flatworms belonging to phylum-Platyhelminthes. They are the simplest from of multicellular animal. The have a high capacity of regeneration of new tissue at the wound site via cell proliferation ( blastema formation) and the remodelling of pre-existing tissue to restore symmetry and proportion. This is due rieoblast cells. 

The cells are usually scattered through out the body and are able to participate in any type of development. The regenerative capacity of different body sections is an indicator of the presence of different numbers of neoblast cells.

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Body having meshwork of cells, internal cavities lined with food filtering flagellated cells and indirect development are the characteristic of phylum

  • Coelenterate

  • Porifera

  • Mollusca

  • Mollusca


B.

Porifera

In Porifera (sponges), bodies are asymmetrical. Body lacks tissues or organs, but from a meshwork of cells surrounding channels that open to the outside through pores, and that expand into internal cavities lined with food filtering flagellated cells (choanocytes).

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Which one of the following living organisms completely lacks a cell wall?

  • Cyanobacteria

  • Sea-fan (Gorgonia)

  • Saccharomyces

  • Saccharomyces


B.

Sea-fan (Gorgonia)

Sea-fan (Gorgonia) belongs to Kingdom-Animalia Phylom, Cnidaria and order: Gorgonacea. As it is on the animal, thus it lacks cell wall cyanobacteria of B we green algae (kingdom Monera) have a cell wall which is composed of peptidoglycan.

Saccharomyces is a genus of kingdom fungi which includes many species of yeast. Their cell wall is mode up of chitin

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