Questions on Invertebrate Diversity, Evolution, and Classification
Invertebrate Diversity, Evolution, and Classification
Multiple-Choice Questions (MCQs)
1. Which of the following groups is exclusively invertebrate?
A) Amphibians
B) Mammals
C) Arthropods
D) Reptiles
E) Chordates
2. Which of these characteristics is typical of all invertebrates?
A) Possession of a backbone
B) Open circulatory system
C) Lack of a vertebral column
D) Endoskeleton
E) Hair or fur
3. Which phylum includes animals like flatworms?
A) Mollusca
B) Arthropoda
C) Platyhelminthes
D) Annelida
E) Echinodermata
4. What type of body symmetry do cnidarians exhibit?
A) Bilateral
B) Asymmetrical
C) Pentamerous radial
D) Radial
E) Spherical
5. The evolutionary advantage of segmentation is most evident in which group?
A) Cnidarians
B) Arthropods
C) Echinoderms
D) Sponges
E) Mollusks
6. Which of the following is a pseudocoelomate?
A) Earthworm
B) Roundworm
C) Tapeworm
D) Leech
E) Snail
7. The exoskeleton of arthropods is primarily composed of:
A) Collagen
B) Chitin
C) Keratin
D) Calcium carbonate
E) Silica
8. Mollusks typically have all of the following EXCEPT:
A) Mantle
B) Foot
C) Notochord
D) Radula (in many)
E) Visceral mass
9. Which group is characterized by a water vascular system?
A) Mollusca
B) Arthropoda
C) Echinodermata
D) Platyhelminthes
E) Cnidaria
10. Which of these is an example of a sessile invertebrate as an adult?
A) Octopus
B) Coral
C) Worm
D) Crab
E) Squid
11. Which of the following invertebrates has a closed circulatory system?
A) Insect
B) Snail
C) Earthworm
D) Jellyfish
E) Starfish
12. Animals that have both male and female reproductive organs are called:
A) Dioecious
B) Monogamous
C) Oviparous
D) Hermaphroditic
E) Parthenogenetic
13. Sponges are classified under the phylum:
A) Echinodermata
B) Porifera
C) Mollusca
D) Annelida
E) Nematoda
14. Which of the following phyla exhibits radial symmetry as adults but bilateral symmetry as larvae?
A) Arthropoda
B) Mollusca
C) Echinodermata
D) Nematoda
E) Annelida
15. The stinging cells found in cnidarians are called:
A) Choanocytes
B) Nematocysts
C) Nephridia
D) Cnidoblasts
E) Spiracles
16. Which of the following is a feature of annelids?
A) Jointed legs
B) Segmented body
C) Exoskeleton
D) Radial symmetry
E) Tentacles
17. Invertebrates make up what percentage of all known animal species?
A) About 10%
B) About 25%
C) About 50%
D) About 75%
E) More than 95%
18. Which phylum contains the most species?
A) Mollusca
B) Annelida
C) Arthropoda
D) Echinodermata
E) Cnidaria
19. Which of the following is not an arthropod?
A) Crab
B) Spider
C) Scorpion
D) Clam
E) Centipede
20. Which class of mollusks includes snails and slugs?
A) Bivalvia
B) Cephalopoda
C) Gastropoda
D) Polyplacophora
E) Scaphopoda
21. Which of the following animals undergoes complete metamorphosis?
A) Earthworm
B) Grasshopper
C) Butterfly
D) Flatworm
E) Snail
22. Which of these groups is acoelomate?
A) Nematoda
B) Annelida
C) Platyhelminthes
D) Mollusca
E) Arthropoda
23. Cephalopods are noted for their:
A) Sessile lifestyle
B) External shells only
C) Highly developed nervous system
D) Filter-feeding
E) Lack of mobility
24. Which invertebrate group has antennae, jointed appendages, and exoskeletons?
A) Mollusks
B) Annelids
C) Arthropods
D) Cnidarians
E) Echinoderms
25. Which of the following is NOT true about echinoderms?
A) They are marine animals
B) They have a water vascular system
C) They exhibit bilateral symmetry as adults
D) They move using tube feet
E) They include starfish and sea urchins
26. Which of the following invertebrates shows bilateral symmetry?
A) Sponge
B) Coral
C) Starfish (adult)
D) Planarian
E) Sea anemone
27. Which of the following animals is an example of a nematode?
A) Tapeworm
B) Hookworm
C) Earthworm
D) Planarian
E) Sea cucumber
28. The radula is used by some mollusks to:
A) Swim
B) See
C) Reproduce
D) Feed
E) Attach to rocks
29. What is the primary habitat of echinoderms?
A) Freshwater
B) Soil
C) Marine
D) Brackish swamps
E) Terrestrial
30. Which phylum includes animals with stinging tentacles and no brain?
A) Mollusca
B) Arthropoda
C) Cnidaria
D) Platyhelminthes
E) Echinodermata
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Answer Key with Explanations
1. C – Arthropods are entirely invertebrate, unlike other groups listed.
2. C – Invertebrates lack a vertebral column.
3. C – Flatworms belong to Platyhelminthes.
4. D – Cnidarians exhibit radial symmetry.
5. B – Arthropods show clear segmentation (head, thorax, abdomen).
6. B – Roundworms are pseudocoelomates.
7. B – The arthropod exoskeleton is made of chitin.
8. C – Mollusks don’t have a notochord; that's a chordate trait.
9. C – Echinoderms use a water vascular system for movement and feeding.
10. B – Adult corals are sessile (attached to one place).
11. C – Earthworms have a closed circulatory system.
12. D – Hermaphroditic organisms have both reproductive organs.
13. B – Sponges are in Porifera.
14. C – Echinoderms have bilateral larvae but radial adults.
15. B – Nematocysts are the stinging structures of cnidarians.
16. B – Annelids (like earthworms) have segmented bodies.
17. E – Over 95% of animal species are invertebrates.
18. C – Arthropoda is the most diverse animal phylum.
19. D – Clams are mollusks, not arthropods.
20. C – Gastropods include snails and slugs.
21. C – Butterflies undergo complete metamorphosis (egg, larva, pupa, adult).
22. C – Platyhelminthes are acoelomates (no body cavity).
23. C – Cephalopods (like octopus) have advanced nervous systems.
24. C – Arthropods have antennae, jointed legs, and exoskeletons.
25. C – Adult echinoderms are radially, not bilaterally, symmetrical.
26. D – Planarians have bilateral symmetry.
27. B – Hookworms are nematodes (roundworms).
28. D – Radula is used for scraping food.
29. C – Echinoderms are exclusively marine.
30. C – Cnidarians have stinging tentacles and no central brain.
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