Q11. Organisms belonging to the phylum Cnidaria typically exhibit which type of symmetry?
a) Bilateral symmetry
b) Radial symmetry
c) Asymmetry
d) Spherical symmetry
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Correct Answer: b) Radial symmetry
Explanation: Cnidarians, such as jellyfish and sea anemones, exhibit radial symmetry, meaning they are arranged around a central axis, like spokes on a wheel. This allows them to capture prey and respond to stimuli from any direction.
Q12. The phylum Porifera is characterized by the presence of:
a) Nematocysts
b) Exoskeletons
c) Pores and canals
d) Stinging cells
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Correct Answer: c) Pores and canals
Explanation: Poriferans, or sponges, possess a porous body structure with numerous openings called pores and a system of canals through which water flows. These canals help sponges filter food particles and oxygen from the water.
Q13. Which of the following phyla includes organisms with a notochord, dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail at some stage of their development?
a) Mollusca
b) Annelida
c) Chordata
d) Echinodermata
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Correct Answer: c) Chordata
Explanation: Chordates are characterized by the presence of these key features at some stage of their development. This phylum includes vertebrates (such as fish, amphibians, reptiles, birds, and mammals) as well as some invertebrate groups.
Q14. The phylum Echinodermata includes organisms such as:
a) Earthworms
b) Sea stars
c) Snails
d) Insects
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Correct Answer: b) Sea stars
Explanation: Echinoderms, such as sea stars (starfish), sea urchins, and sea cucumbers, belong to the phylum Echinodermata. They are characterized by radial symmetry, a unique
Q15. Members of the phylum Mollusca include organisms such as:
a) Earthworms
b) Jellyfish
c) Snails
d) Coral
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Correct Answer: c) Snails
Explanation: Mollusks, or molluscs, are a diverse group of invertebrates that include snails, clams, octopuses, and squids. They typically have soft bodies, a muscular foot, and may possess a hard shell for protection.
Q16. Which of the following phyla includes organisms that are often segmented and possess a coelom (body cavity)?
a) Porifera
b) Platyhelminthes
c) Annelida
d) Cnidaria
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Correct Answer: c) Annelida
Explanation: Annelids, such as earthworms and leeches, are segmented worms with bodies composed of repeating units called segments. They possess a true coelom, a fluid-filled body cavity surrounded by mesoderm.
Q17. The phylum Arthropoda is characterized by the presence of:
a) Soft bodies and often possess a hard shell
b) Segmented bodies and jointed appendages
c) Radial symmetry and a water vascular system
d) Metamorphosis and a notochord
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Correct Answer: b) Segmented bodies and jointed appendages
Explanation: Arthropods, such as insects, spiders, crustaceans, and centipedes, have segmented bodies and jointed appendages. They are the most diverse and abundant group of animals on Earth.
Q18. Organisms belonging to the phylum Nematoda are commonly known as:
a) Roundworms
b) Flatworms
c) Segmented worms
d) Tapeworms
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Correct Answer: a) Roundworms
Explanation: Nematodes, or roundworms, are unsegmented worms with elongated, cylindrical bodies. They are found in diverse habitats, including soil, water, and as parasites of plants and animals.
Q19. The phylum Cnidaria includes organisms such as:
a) Flatworms
b) Roundworms
c) Jellyfish
d) Earthworms
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Correct Answer: c) Jellyfish
Explanation: Cnidarians, such as jellyfish, sea anemones, and corals, belong to the phylum Cnidaria. They are characterized by radial symmetry, specialized stinging cells called cnidocytes, and a simple body plan.
Q20. Which of the following phyla includes organisms that are known for their diverse array of body forms and often possess a water vascular system?
a) Arthropoda
b) Echinodermata
c) Mollusca
d) Platyhelminthes
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Correct Answer: b) Echinodermata
Explanation: Echinoderms, such as sea stars, sea urchins, and sea cucumbers, exhibit a wide range of body forms and possess a unique water vascular system used for locomotion, feeding, and gas exchange.