Calcarea MCQs December 4, 2025September 30, 2024 by u930973931_answers 30 min Score: 0 Attempted: 0/30 Subscribe 1. What is the primary characteristic of sponges in the class Calcarea? (A) They have siliceous spicules. (B) They have organic spicules. (C) They lack spicules. (D) They have calcium carbonate spicules. 2. Which of the following habitats do Calcarea sponges primarily occupy? (A) Freshwater (B) Marine (C) Terrestrial (D) Brackish water 3. What type of body plan is commonly found in Calcarea sponges? (A) Both A and B (B) Syconoid (C) Leuconoid (D) Asconoid 4. What is the main composition of the spicules in Calcarea sponges? (A) Calcium carbonate (B) Silica (C) Chitin (D) Protein 5. Which of the following is a genus of sponges found in the class Calcarea? (A) Chlamydomonas (B) Oscillatoria (C) Clathrina (D) Amoeba 6. Calcarea sponges reproduce in which of the following ways? (A) Both sexually and asexually (B) Only asexually (C) Only sexually (D) Neither sexually nor asexually 7. What is the primary role of choanocytes in Calcarea sponges? (A) Structural support (B) Food digestion (C) Water circulation and filtering (D) Reproduction 8. Which feature distinguishes Calcarea sponges from other sponge classes? (A) Presence of calcium carbonate spicules (B) Presence of oscula (C) Presence of siliceous spicules (D) Presence of flagellated cells 9. What is the typical size range of Calcarea sponges? (A) Over 5 m (B) 1 cm to 1 m (C) 1 m to 5 m (D) 1 mm to 10 cm 10. What is the ecological role of Calcarea sponges? (A) Predators (B) Filter feeders (C) Primary producers (D) Decomposers 11. How do Calcarea sponges primarily obtain their food? (A) Filter feeding (B) Photosynthesis (C) Predation (D) Absorption through skin 12. Which of the following structures is involved in water flow in Calcarea sponges? (A) All of the above (B) Spongocoel (C) Pores (D) Osculum 13. What type of symmetry do Calcarea sponges exhibit? (A) Bilateral symmetry (B) Radial symmetry (C) Asymmetry (D) None of the above 14. What is the larval stage of Calcarea sponges called? (A) Planula (B) Trochophore (C) Parenchymella (D) Veliger 15. Which is a characteristic feature of class Calcarea? (A) Always brightly colored (B) Possess a spongin skeleton (C) Form large colonies (D) Small, tubular bodies 16. What structure do Calcarea sponges use for excretion? (A) Flagella (B) Pores (C) Choanocytes (D) Osculum 17. Calcarea sponges typically have which feature? (A) Low metabolic rates (B) High reproductive rates (C) Thick walls (D) Complex canal systems 18. What is a function of the mesohyl in Calcarea sponges? (A) Water circulation (B) Nutrient transport (C) Structural support (D) All of the above 19. What is the habitat preference of Calcarea sponges? (A) Deep sea (B) Freshwater (C) Coastal marine waters (D) Intertidal zones 20. Which of the following is true about Calcarea sponges? (A) Exclusively freshwater (B) Lack sexual reproduction (C) Both solitary and colonial (D) Largest sponges 21. In terms of biodiversity, Calcarea sponges are considered: (A) Highly diverse (B) Low diversity (C) Moderately diverse (D) Non-diverse 22. What is a common predator of Calcarea sponges? (A) Sea stars (B) Fish (C) Sea turtles (D) Crabs 23. How do Calcarea sponges respond to environmental changes? (A) Remain unchanged (B) Adapt quickly (C) Migrate (D) Sensitive and may decline 24. Which reproductive strategies are common in Calcarea sponges? (A) Budding (B) Fission (C) Fragmentation (D) All of the above 25. What is the main threat to Calcarea sponges? (A) Climate change (B) All of the above (C) Habitat destruction (D) Overfishing 26. Calcarea sponges are primarily found in which type of water? (A) Saline (B) Freshwater (C) Brackish (D) Ice-cold 27. Which characteristic makes Calcarea sponges unique? (A) Presence of spongin (B) Organic spicules (C) Hard skeleton (D) Siliceous spicules 28. What is the typical coloration of Calcarea sponges? (A) Bright red (B) Green (C) Bioluminescent (D) Muted colors 29. Which type of canal system is NOT found in Calcarea sponges? (A) Asconoid (B) Syconoid (C) None of the above (D) Leuconoid 30. What role do spicules play in Calcarea sponges? (A) Digestion (B) Protection and support (C) Reproduction (D) Locomotion