Q31. The phylum Arthropoda is characterized by the presence of:
a) A notochord and a dorsal hollow nerve cord
b) Radial symmetry and a water vascular system
c) Segmented bodies and jointed appendages
d) A muscular foot and often possess a hard shell
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Correct Answer: c) Segmented bodies and jointed appendages
Explanation: Arthropods, such as insects, spiders, crustaceans, and centipedes, have segmented bodies and jointed appendages, which allow for diverse movements and functions.
Q32. Members of the phylum Mollusca often possess a hard external shell composed primarily of:
a) Calcium carbonate
b) Silica
c) Chitin
d) Cellulose
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Correct Answer: a) Calcium carbonate
Explanation: The shells of mollusks, such as snails, clams, and octopuses, are primarily composed of calcium carbonate, providing protection and structural support.
Q33. The phylum Chordata includes organisms that exhibit which type of symmetry?
a) Bilateral symmetry
b) Radial symmetry
c) Asymmetry
d) Spherical symmetry
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Correct Answer: a) Bilateral symmetry
Explanation: Chordates, which include vertebrates and some invertebrates, exhibit bilateral symmetry, meaning their bodies can be divided into two similar halves along a central plane.
Q34. Organisms belonging to the phylum Porifera lack which of the following features?
a) Digestive system
b) Nervous system
c) Respiratory system
d) Excretory system
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Correct Answer: a) Digestive system
Explanation: Poriferans, or sponges, lack a true digestive system. They obtain nutrients by filtering food particles from water that enters through pores in their bodies.
Q35. The phylum Cnidaria includes organisms that primarily exist in which of the following environments?
a) Terrestrial
b) Freshwater
c) Marine
d) Polar
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Correct Answer: c) Marine
Explanation: Cnidarians, such as jellyfish and corals, are predominantly found in marine environments, although some species inhabit freshwater habitats as well.
Q36. Members of the phylum Annelida are characterized by the presence of which of the following structures for locomotion?
a) Setae
b) Tentacles
c) Pseudopodia
d) Cilia
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Correct Answer: a) Setae
Explanation: Annelids, such as earthworms and leeches, possess bristly appendages called setae, which aid in locomotion by providing traction against the substrate.
Q37. The phylum Echinodermata includes organisms that typically exhibit which of the following body plans?
a) Bilateral symmetry
b) Asymmetry
c) Pentaradial symmetry
d) Spherical symmetry
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Correct Answer: c) Pentaradial symmetry
Explanation: Echinoderms, such as sea stars and sea urchins, exhibit pentaradial symmetry, meaning their bodies can be divided into five similar parts radiating from a central axis.
Q38. Organisms belonging to the phylum Nematoda are commonly known for their:
a) Segmented bodies
b) Soft, flattened bodies
c) Round, cylindrical bodies
d) Elongated, ribbon-like bodies
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Correct Answer: c) Round, cylindrical bodies
Explanation: Nematodes, or roundworms, have elongated, cylindrical bodies, which are tapered at both ends. They are unsegmented and exhibit a high degree of diversity in form and habitat.
Q39. The phylum Platyhelminthes includes organisms that are often characterized by which of the following features?
a) Segmented bodies and jointed appendages
b) Soft, flattened bodies with bilateral symmetry
c) Radial symmetry and tentacles
d) Hard, calcareous shells
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Correct Answer: b) Soft, flattened bodies with bilateral symmetry
Explanation: Platyhelminths, or flatworms, have soft, flattened bodies with bilateral symmetry. They include free-living species like planarians and parasitic species like tapeworms.
Accordion title 2
Q40. Which of the following is a characteristic feature of the phylum Chordata?
a) Presence of jointed appendages
b) Exoskeleton made of chitin
c) Dorsal hollow nerve cord
d) Segmented bodies
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Correct Answer: c) Dorsal hollow nerve cord
Explanation: Chordates are characterized by the presence of a dorsal hollow nerve cord, which develops into the spinal cord in vertebrates. This nerve cord is one of the defining features of the phylum.