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2.2 Porifera — Test 1
Q1. Collar cells (choanocytes) are characteristically present in members of the phylum:✓ Porifera
Q2. Fertilisation in Sycon (a sponge) occurs:✓ Internally, within the body wall
Q3. The principal cell types in the body wall of a calcareous sponge include:✓ Pinacocytes, porocytes, choanocytes and amoebocytes
Q4. Gemmules in freshwater sponges function in:✓ Asexual reproduction and surviving harsh conditions
Q5. The free-swimming larva of a sponge is the:✓ Amphiblastula (or parenchymula)
Q6. The totipotent cells of sponges, able to form any other cell type, are the:✓ Archaeocytes
Q7. The canal system, a network of water channels, is characteristic of the phylum:✓ Porifera
Q8. Cliona celata is commonly known as the:✓ Boring sponge
Q9. Spongilla is a sponge found in:✓ Fresh water
Q10. The circular sphincter around the osculum of a sponge is formed by:✓ Myocytes
Q11. In sponges, the incurrent canal communicates with the radial canal through the:✓ Prosopyle
Q12. Six-rayed (triaxon) siliceous spicules are characteristic of the glass sponge:✓ Euplectella
Q13. Spicules in calcareous sponges are made of:✓ Calcium carbonate
2.2 Porifera — Test 2
Q14. The osculum of a sponge serves mainly as the:✓ Exit for the outgoing water current
Q15. Sponges belong to the group Parazoa because they:✓ Lack true tissues and organs
Q16. Calcium and magnesium ions are necessary for sponge cells to:✓ Reaggregate during regeneration
Q17. The body wall of a simple ascon sponge encloses a central cavity called the:✓ Spongocoel (paragastric cavity)
Q18. Which of the following is NOT a characteristic of the phylum Porifera?✓ Presence of a true nervous system
Q19. Digestion in sponges is:✓ Intracellular (within cells)
Q20. Leuconoid sponges are more efficient than ascon sponges because they have:✓ More numerous flagellated chambers and greater surface area
Q21. Sponges reproduce asexually mainly by:✓ Budding and gemmule formation
Q22. The boring sponge damages oyster beds by:✓ Excavating tunnels in the calcareous shells
Q23. Reproduction by which sponges release larvae shows that sponges have a:✓ Sexual phase with a ciliated larval stage
Q24. The skeleton of a bath sponge is made of the flexible protein:✓ Spongin
Q25. Amoebocytes (archaeocytes) in sponges perform all of these EXCEPT:✓ Generating nerve impulses
2.2 Porifera — Test 3
Q26. In sponges, water enters through the ostia and leaves through the:✓ Osculum
Q27. Sponges are placed at the base of the animal kingdom because they:✓ Show the simplest, cellular grade of body organisation
Q28. Skeletal spicules in sponges are secreted by special cells called:✓ Sclerocytes
Q29. Which feature best shows that sponges are multicellular but primitive?✓ Division of labour among loosely organised cells without true tissues
Q30. The pinacocytes of a sponge function to:✓ Form the outer covering (pinacoderm) of the body
Q31. A sponge differs fundamentally from a cnidarian in that the sponge:✓ Lacks true tissues, nerve cells and a mouth
Q32. The flagellated collar cells that create the feeding current in sponges are the:✓ Choanocytes
Q33. Most sponges are:✓ Marine and sessile filter feeders
Q34. The simplest type of canal system in sponges, with choanocytes lining the spongocoel directly, is the:✓ Ascon type
Q35. Sponge cells dissociated by passing through fine cloth can:✓ Reaggregate and reform a functional sponge
Q36. Sponges obtain food and oxygen mainly by:✓ Filtering water passing through the body
Q37. The presence of choanocytes in sponges suggests they evolved from ancestors resembling:✓ Choanoflagellate protozoans