Q1. Which phylum of animals includes organisms commonly known as sponges?
a) Porifera
b) Coelenterata (Cnidaria)
c) Platyhelminthes
d) Annelida
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Correct Answer: a) Porifera
Explanation: Porifera, commonly known as sponges, are simple multicellular organisms lacking true tissues. They are filter feeders that live in aquatic environments, and their body plan consists of numerous pores and channels for water flow, which allows them to trap food particles.
Q2. Animals belonging to which phylum have a central cavity with a single opening, the mouth?
a) Porifera
b) Coelenterata (Cnidaria)
c) Platyhelminthes
d) Mollusca
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Correct Answer: b) Coelenterata (Cnidaria)
Explanation: Coelenterata, also known as Cnidaria, includes organisms such as jellyfish and sea anemones. They possess a central cavity called a coelenteron, which serves as both the digestive and circulatory system, with a single opening serving as both mouth and anus.
Q3. Animals belonging to the phylum Ctenophora are commonly known as:
a) Jellyfish
b) Comb jellies
c) Flatworms
d) Roundworms
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Correct Answer: b) Comb jellies
Explanation: Ctenophora, or comb jellies, are marine animals characterized by their translucent, gelatinous bodies and rows of cilia used for locomotion. Unlike cnidarians, they possess adhesive cells called colloblasts for capturing prey.
Q4. Which of the following phyla includes organisms with bilateral symmetry and a solid body without a body cavity?
a) Porifera
b) Coelenterata (Cnidaria)
c) Platyhelminthes
d) Annelida
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Correct Answer: c) Platyhelminthes
Explanation: Platyhelminthes, or flatworms, are dorsoventrally flattened animals with bilateral symmetry. They lack a true body cavity (coelom) and possess a solid body structure. Examples include tapeworms and planarians.
Q5. Roundworms belong to which phylum of animals?
a) Platyhelminthes
b) Aschelminthes
c) Annelida
d) Arthropoda
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Correct Answer: b) Aschelminthes
Explanation: Aschelminthes, also known as nematodes or roundworms, are unsegmented worms with cylindrical bodies. They possess a complete digestive system and are found in diverse habitats ranging from soil to marine environments.
Q6. Earthworms belong to which phylum of animals?
a) Annelida
b) Arthropoda
c) Mollusca
d) Echinodermata
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Correct Answer: a) Annelida
Explanation: Annelida comprises segmented worms, including earthworms, leeches, and marine polychaetes. They exhibit bilateral symmetry and possess a true coelom, with a segmented body divided by septa.
Q7. Which of the following phyla includes animals with jointed appendages and an exoskeleton made of chitin?
a) Annelida
b) Arthropoda
c) Mollusca
d) Echinodermata
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Correct Answer: b) Arthropoda
Explanation: Arthropods are characterized by their jointed appendages and exoskeleton composed of chitin. This phylum includes insects, arachnids, crustaceans, and myriapods, making it the largest and most diverse group of animals.
Q8. Animals belonging to the phylum Mollusca commonly possess which of the following features?
a) Jointed appendages
b) A segmented body
c) A mantle and a shell
d) A water vascular system
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Correct Answer: c) A mantle and a shell
Explanation: Mollusks typically possess a soft body covered by a mantle, which often secretes a calcareous shell for protection. Examples include snails, clams, octopuses, and squid.
Q9. Which phylum of animals includes organisms such as sea stars and sea urchins?
a) Mollusca
b) Echinodermata
c) Annelida
d) Hemichordata
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Correct Answer: b) Echinodermata
Explanation: Echinoderms are characterized by their spiny skin and radial symmetry in adulthood. They possess a water vascular system used for locomotion, feeding, and gas exchange. Examples include sea stars, sea urchins, and sea cucumbers.
Q10. Which of the following phyla includes organisms with a notochord and a dorsal nerve cord?
a) Mollusca
b) Echinodermata
c) Annelida
d) Hemichordata
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Correct Answer: d) Hemichordata
Explanation: Hemichordates are marine organisms possessing a notochord and a dorsal nerve cord, similar to the chordates. However, they lack a true vertebral column. Examples include acorn worms and pterobranchs.