Questions on Cnidarians (Animal Kingdom)
Cnidarians – Multiple-Choice Questions
1. Cnidarians are characterized by the presence of:
A) Cilia
B) Tentacles with cilia
C) Nematocysts
D) Segmentation
E) Exoskeletons
2. Which of the following is not a class of Cnidarians?
A) Hydrozoa
B) Scyphozoa
C) Cubozoa
D) Turbellaria
E) Anthozoa
3. The two main body forms of Cnidarians are:
A) Bilateral and radial
B) Larva and adult
C) Medusa and polyp
D) Shell and no shell
E) Tentacled and non-tentacled
4. Cnidarians exhibit which type of body symmetry?
A) Bilateral
B) Asymmetrical
C) Spherical
D) Radial
E) Spiral
5. What is the main function of nematocysts in cnidarians?
A) Respiration
B) Digestion
C) Reproduction
D) Capturing prey and defense
E) Locomotion
6. Which of the following cnidarians has a dominant polyp stage?
A) Jellyfish
B) Coral
C) Sea wasp
D) Box jellyfish
E) Sea nettle
7. The digestive system of cnidarians includes:
A) A complete alimentary canal
B) A coelom
C) A gastrovascular cavity
D) Multiple stomachs
E) A true gut with anus
8. Cnidarians are:
A) Protostomes
B) Acoelomate deuterostomes
C) Diploblastic animals
D) Triploblastic animals
E) Unicellular organisms
9. What tissue layers do cnidarians possess?
A) Ectoderm and mesoderm
B) Endoderm and mesoderm
C) Ectoderm and endoderm
D) Mesoderm only
E) No tissue layers
10. Which class of cnidarians includes true jellyfish?
A) Anthozoa
B) Hydrozoa
C) Cubozoa
D) Scyphozoa
E) Platyhelminthes
11. Coral reefs are built primarily by:
A) Medusae
B) Hydrozoans
C) Anthozoans
D) Cubozoans
E) Sponges
12. In cnidarians, what structure controls simple movements?
A) Brain
B) Spinal cord
C) Nerve net
D) Muscle fibers
E) Ganglia
13. The cnidarian class Hydrozoa often exhibits:
A) Only polyp forms
B) Only medusa forms
C) No symmetry
D) Alternation of polyp and medusa forms
E) Colonial sponges
14. Sea anemones belong to which class?
A) Hydrozoa
B) Anthozoa
C) Scyphozoa
D) Cubozoa
E) Turbellaria
15. What is a common characteristic of all cnidarians?
A) Presence of exoskeleton
B) Lack of nervous system
C) Filter feeding
D) Tentacles with stinging cells
E) Bilateral symmetry
16. The term Cnidaria refers to:
A) Hollow body
B) Radial symmetry
C) Stinging cells
D) Aquatic lifestyle
E) Coral-building
17. Which cnidarian is known for being extremely venomous?
A) Moon jelly
B) Hydra
C) Sea fan
D) Portuguese man o’ war
E) Box jellyfish
18. Cnidarians excrete waste primarily by:
A) Nephridia
B) Gills
C) Flame cells
D) Diffusion through the body wall
E) Specialized excretory organs
19. Cnidarians use which method for gas exchange?
A) Gills
B) Lungs
C) Spiracles
D) Tracheae
E) Diffusion
20. The dominant stage in the life cycle of Scyphozoa is:
A) Polyp
B) Planula
C) Medusa
D) Larva
E) Cyst
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Answers with Explanations
1. C) Nematocysts – Specialized stinging cells used for capturing prey and defense.
2. D) Turbellaria – This is a class of flatworms (Platyhelminthes), not cnidarians.
3. C) Medusa and polyp – The two main body forms; some cnidarians alternate between both.
4. D) Radial – Cnidarians exhibit radial symmetry, allowing interaction from all sides.
5. D) Capturing prey and defense – Nematocysts are stinging organelles.
6. B) Coral – Corals are primarily in the polyp stage throughout life.
7. C) A gastrovascular cavity – A central cavity where digestion and circulation occur.
8. C) Diploblastic animals – They have two germ layers: ectoderm and endoderm.
9. C) Ectoderm and endoderm – These form their outer and inner tissue layers.
10. D) Scyphozoa – Known as true jellyfish, with dominant medusa form.
11. C) Anthozoans – Coral species fall under this class.
12. C) Nerve net – A decentralized nerve structure for basic responses.
13. D) Alternation of polyp and medusa forms – Hydrozoa often exhibit both forms.
14. B) Anthozoa – This class includes sea anemones and corals.
15. D) Tentacles with stinging cells – A universal feature in cnidarians.
16. C) Stinging cells – “Cnidaria” is derived from “cnidos,” meaning nettle or sting.
17. E) Box jellyfish – Among the most venomous animals on Earth.
18. D) Diffusion through the body wall – Simple organisms like cnidarians rely on diffusion.
19. E) Diffusion – Gas exchange occurs across their body surfaces.
20. C) Medusa – Scyphozoans spend most of their life in the medusa (jellyfish) form.
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