Phylum Orthonectida MCQs December 5, 2025September 28, 2024 by u930973931_answers 30 min Score: 0 Attempted: 0/30 Subscribe 1. Orthonectida are primarily classified as which type of organism? (A) Protozoa (B) Marine invertebrates (C) Parasites (D) Plants 2. What type of body structure do orthonectids exhibit? (A) Segmented body (B) Radial symmetry (C) Asymmetrical body (D) Bilateral symmetry 3. Orthonectids are known to primarily inhabit which environment? (A) Marine (B) Terrestrial (C) Freshwater (D) Aerial 4. The main mode of nutrition for orthonectids is: (A) Photosynthesis (B) Filter feeding (C) Absorption of nutrients from the host (D) Predation 5. Which organisms are common hosts for orthonectids? (A) Mollusks (B) Annelids (C) Echinoderms (D) Arthropods 6. The life cycle of orthonectids is typically characterized by: (A) Complex metamorphosis (B) Direct development (C) Multiple larval stages (D) Asexual reproduction 7. Which best describes the body structure of orthonectids? (A) Well-defined organs (B) Presence of chitinous exoskeleton (C) Possession of a true coelom (D) Cellular organization without tissues 8. Orthonectids are closely related to which group of organisms? (A) Cnidarians (B) Flatworms (C) Tardigrades (D) Nematodes 9. The primary mode of reproduction in orthonectids is: (A) Asexual reproduction (B) Sexual reproduction (C) Budding (D) Fragmentation 10. A significant characteristic of orthonectids that aids in their parasitic lifestyle is: (A) Ability to photosynthesize (B) Complex nervous system (C) Ability to penetrate host tissues (D) Hard exoskeleton 11. The developmental stages of orthonectids include: (A) Egg, juvenile, adult (B) Egg, larva, adult (C) Spore, larva, adult (D) Egg, trophozoite, adult 12. Orthonectids are characterized by their unique method of: (A) Locomotion (B) Host manipulation (C) Feeding (D) Respiration 13. Which of the following is NOT a characteristic of orthonectids? (A) Bilateral symmetry (B) Complex digestive systems (C) Lack of specialized respiratory structures (D) Ability to reproduce in the host 14. Orthonectids are typically found in which part of their host? (A) In the muscles (B) In the digestive tract (C) In the blood (D) In the exoskeleton 15. Which statement about orthonectids is true? (A) They are known for their ability to cause disease in hosts. (B) They have a complex lifecycle with many larval forms. (C) They are strictly free-living organisms. (D) They lack any form of locomotion. 16. The main ecological role of orthonectids is as: (A) Primary producers (B) Decomposers (C) Parasites in marine ecosystems (D) Filter feeders 17. Orthonectids are often studied for their: (A) Economic importance (B) Ecological impact on host species (C) Role in food chains (D) Aesthetic value 18. The typical size range of orthonectids is: (A) Several meters long (B) Centimeter to meter scale (C) Meter to kilometer scale (D) Microscopic to millimeter scale 19. The locomotion of orthonectids primarily involves: (A) Flagella (B) Pseudopodia (C) Cilia (D) Muscle contraction 20. Orthonectids are classified within which broader group? (A) Parazoa (B) Ecdysozoa (C) Deuterostomia (D) Lophotrochozoa 21. The primary method by which orthonectids obtain nutrients from their hosts is: (A) Filter feeding (B) Absorption through the skin (C) Symbiotic relationships (D) Parasitic feeding mechanisms 22. Orthonectids can be identified by their distinct: (A) Coloration (B) Body plan (C) Feeding habits (D) Reproductive strategies 23. In terms of evolutionary significance, orthonectids provide insight into: (A) The evolution of parasitism (B) The evolution of complex multicellularity (C) The origin of vertebrates (D) The diversification of marine life 24. Orthonectids are typically characterized by their: (A) High metabolic rates (B) Limited mobility (C) Lack of a nervous system (D) Ability to undergo metamorphosis 25. The reproduction process of orthonectids involves: (A) Budding (B) Internal fertilization (C) Parthenogenesis (D) External fertilization 26. Orthonectids have a simple body structure composed mainly of: (A) A single layer of cells (B) Ectoderm and mesoderm (C) Endoderm only (D) Complex organ systems 27. The primary scientific interest in orthonectids relates to their: (A) Habitat preferences (B) Role in marine food webs (C) Parasitic adaptations (D) Ecological relationships 28. What kind of lifestyle do orthonectids lead? (A) Fully aquatic (B) Parasitic (C) Terrestrial (D) Saprophytic 29. The reproductive strategy of orthonectids is: (A) Asexual reproduction only (B) Both asexual and sexual reproduction (C) Sexual reproduction only (D) Budding only 30. Orthonectids contribute to our understanding of: (A) Host-pathogen interactions (B) Evolution of terrestrial life (C) Plant-animal interactions (D) Marine conservation