SUBJECTIVE QUESTIONS

SUBJECTIVE QUESTIONS

  1. Give evolutionary perspective of Molluscs.
  2. Give different hypothesis about the evolution of coelom.
  3. Give general characteristics of molluscs.
  4. Write note on shell of molluscs.
  5. Write note on radula.
  6. Give classification of molluscs.
  7. What is torsion? Give its advantages and disadvantage.
  8. Discuss feeding and digestion in molluscs.
  9. Describe respiration and circulation in molluscs.
  10. Describe locomotion in molluscs.
  11. Give nervous system of molluscs.
  12. Give excretory system of molluscs.
  13. Write note on gastropods.
  14. Write note on shell of Bivalve.
  15. Give respiration in molluscs.
  16. Discuss nutrition in bivalves.
  17. Give blood vascular system, excretion and nervous system in bivalves.
  18. Describe development in bivalves.
  19. Write note on bivalve diversity.
  20. Give characteristics of Cephalopoda.
  21. Write note on shell in cephalopods.
  22. Give locomotion in cephalopods
  23. Discuss nutrition in cephalopods.
  24. Write note on blood vascular system in cephalopods.
  25. Give sense organs in cephalopods.
  26. How are colour developed in the cephalopods.
  27. Discuss reproduction and development in cephalopods.
  28. Discuss protostome and molluscs ancestry.

SHORT QUESTIONS

1. What is coelom?

Ans: A coelom is a. body cavity that arises in mesoderm and is lined by a sheet of mesoderm called the peritoneum.

2. What are protostomes?

Ans: The animals in which blastopore form mouth are called protostomes.

3. What are the similarities between molluscs and annelids?

Ans: Both have similar trochophore larvae. Certain adult structures of molluscs and annelids are similar. For example. the excretory organs and their duct systems are similar in them.

4. What are enterocoelous?

Ans: The animals in which coelom are formed by invagination of enteron or gut are called enterocoelous.

5. What are deutrostomes?

Ans: The animals in which blastopore forms anus and mouth formed as a secondary opening are called deutrostomes.

6. What are schizocoelous?

Ans: The animals which are formed by the splitting of mesoderm are called schizocoelous.

7. What are the body parts of molluscs?

Ans: head-foot and visceral mass

8. What is mantle?

Ans: Mantle of molluscs is attached to the visceral mass It enfolds most of the body. It secreted a shell that overlies the mantle.

9. What is visceral mass?


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Ans: Visceral mass contains the organs of digestion, circulation, reproduction, and excretion. It is present dorsal to the head-foot.

10. Name the three layers of shell.

Ans: Periostracum, Prismatic layer and Nacreous layer

11. Name classes of Phylum .Mollusca.

Ans: Catidotbveata, Aplacophora, Polyplacophora, Monoplacophora, Scaphopoda, Bivalvia, Gastropoda and Cephalopoda.

12. What is torsion?

Ans: Torsion is a 1800, counterclockwise twisting of the visceral mass, mantle, and mantle cavity.

13. What are Osphradia?

Ans: Osphradia are chemoreceptors. They are present in the anterior wall of the mantle cavity. It detects chemicals in inhalant water or air. The osphradia of predatory gastropods detect prey.

14. What are valves?’

Ant: The two convex halves of the shell are called valves.

15. What is umbo?

Ant: The oldest part of the shell is called Limbo. limbo is a swollen area near the shell’s anterior margin.

16. What is the function of adductor muscles?

Ans: Adductor muscles are present at both end of the dorsal half of the shell. They

contract and close the shell.

17. How is pearl formed in bivalve?

Ans: Sometimes, a sand grain or a parasite conies within the shell. The mantle secretes nacre around it and form pearl.

18. Name the bivalve which produces high quality pearl.
Ans:
Pine/oda margarirlfera

19. What is the function of byssal threads?

Ans: They are attached to the substrate by proteinaceous strands called byssal threads.

20. Name the cephalopod in which external shell is present.
Ans:
Nautilus

21. What is pen?

Ans: The shell of a squid is reduced. It has internal, chitinous structure called the pen.

22. What is pinhole camera?

Ans: ‘Me nautiloid eye is less complex. It lacks a lens. Its interior is open to seawater. Thus it acts as a pinhole camera.

23. Which group is the “missing link” between other molluscs and the annelid‑ arthropod evolutionary line?

Ans: Monoplacophorans.

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