Q21. The phylum Chordata is divided into which three subphyla?
a) Urochordata, Cephalochordata, Vertebrata
b) Urochordata, Craniata, Vertebrata
c) Cephalochordata, Craniata, Vertebrata
d) Urochordata, Hemichordata, Vertebrata
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Correct Answer: a) Urochordata, Cephalochordata, Vertebrata
Explanation: The phylum Chordata is divided into three subphyla: Urochordata (tunicates), Cephalochordata (lancelets), and Vertebrata (vertebrates). Each subphylum encompasses organisms with varying levels of complexity and evolutionary advancements.
Q22. Which of the following groups of chordates are often referred to as “protochordates”?
a) Urochordata and Cephalochordata
b) Cephalochordata and Vertebrata
c) Urochordata and Vertebrata
d) Vertebrata and Hemichordata
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Correct Answer: a) Urochordata and Cephalochordata
Explanation: The subphyla Urochordata and Cephalochordata are often referred to as “protochordates” or “primitive chordates.” These groups exhibit characteristics typical of chordates but are less complex than vertebrates.
Q23. In chordates, the pharynx typically contains which structures?
a) Pharyngeal gill slits and endostyle
b) Pharyngeal arches and tentacles
c) Pharyngeal jaws and cilia
d) Pharyngeal pouches and lungs
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Correct Answer: a) Pharyngeal gill slits and endostyle
Explanation: In chordates, the pharynx typically contains pharyngeal gill slits and an endostyle. Pharyngeal gill slits are openings in the pharynx used for filter feeding or respiration, while the endostyle secretes mucus to trap food particles.
Q24. The notochord in chordates is located:
a) Ventral to the digestive tract
b) Dorsal to the central nervous system
c) Posterior to the pharynx
d) Surrounding the heart
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Correct Answer: a) Ventral to the digestive tract
Explanation: The notochord in chordates is located ventral to the digestive tract and dorsal to the nerve cord. It serves as a supportive structure and provides rigidity to the body during embryonic development.
Q25. The presence of a pharynx with slits is a characteristic feature of which group of chordates?
a) Urochordata
b) Cephalochordata
c) Vertebrata
d) Hemichordata
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Correct Answer: a) Urochordata
Explanation: Urochordates, or tunicates, possess a pharynx with slits, known as pharyngeal gill slits. These slits are used for filter feeding or respiration and are characteristic of chordates during at least some stage of their development.
Q26. In chordates, the nerve cord is typically located:
a) Dorsally, above the notochord
b) Ventrally, below the notochord
c) Laterally, alongside the notochord
d) Anteriorly, in front of the notochord
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Correct Answer: a) Dorsally, above the notochord
Explanation: In chordates, the nerve cord is typically located dorsally, above the notochord. This arrangement is a key characteristic of chordates and serves as a defining feature of the phylum.
Q27. The presence of a post-anal tail is a defining characteristic of which group of chordates?
a) Vertebrata
b) Urochordata
c) Cephalochordata
d) Hemichordata
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Correct Answer: a) Vertebrata
Explanation: Vertebrates, belonging to the subphylum Vertebrata, are characterized by the presence of a post-anal tail at some stage of their development. This tail is an extension of the body past the anal opening and is typically lost or reduced in adults of some species.
Q28. The endostyle found in some chordates is functionally analogous to which structure in vertebrates?
a) Thyroid gland
b) Liver
c) Kidney
d) Lung
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Correct Answer: a) Thyroid gland
Explanation: The endostyle, found in some chordates such as tunicates and amphioxus, is functionally analogous to the thyroid gland in vertebrates. It secretes mucus and iodine-containing compounds involved in filter feeding and iodine metabolism, respectively.
Q29. The class Chondrichthyes within the subphylum Vertebrata includes animals with:
a) Cartilaginous skeleton
b) Bony skeleton
c) Exoskeleton
d) Endoskeleton
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Correct Answer: a) Cartilaginous skeleton
Explanation: Chondrichthyans, or cartilaginous fish, belong to the class Chondrichthyes within the subphylum Vertebrata. They possess a skeleton primarily composed of cartilage, making them distinct from osteichthyans (bony fish).
Q30. The amniotic egg, characteristic of reptiles, birds, and some mammals, allows for:
a) External fertilization
b) Development in aquatic environments
c) Terrestrial reproduction
d) Viviparous birth
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Correct Answer: c) Terrestrial reproduction
Explanation: The amniotic egg, characteristic of reptiles, birds, and some mammals, allows for terrestrial reproduction. It contains specialized membranes that protect and nourish the developing embryo, allowing it to develop outside of water.
Q31. Which of the following is a characteristic feature of animals in the class Aves?
a) External fertilization
b) Presence of mammary glands
c) Oviparous reproduction
d) Ectothermy
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Correct Answer: c) Oviparous reproduction
Explanation: Birds, belonging to the class Aves, reproduce via oviparous reproduction, meaning they lay eggs that develop and hatch outside the mother’s body. This adaptation allows for parental care and protection of eggs.
Q32. The presence of feathers is a characteristic feature of which group of chordates?
a) Urochordata
b) Cephalochordata
c) Vertebrata
d) Hemichordata
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Correct Answer: c) Vertebrata
Explanation: Feathers are a characteristic feature of vertebrates, specifically birds (class Aves), within the subphylum Vertebrata. Feathers are specialized integumentary structures that enable flight, insulation, and display in birds.
Q33. The class Mammalia within the subphylum Vertebrata is characterized by which of the following reproductive adaptations?
a) External fertilization
b) Oviparous reproduction
c) Viviparous birth
d) Larval metamorphosis
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Correct Answer: c) Viviparous birth
Explanation: Mammals, belonging to the class Mammalia, typically reproduce via viviparous birth, meaning they give birth to live young that have developed internally within the mother’s body. This reproductive adaptation allows for parental care and protection of offspring.
Q34. Which of the following groups of chordates possesses a notochord only during the larval stage?
a) Urochordata
b) Cephalochordata
c) Vertebrata
d) Hemichordata
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Correct Answer: a) Urochordata
Explanation: Urochordates, also known as tunicates or sea squirts, possess a notochord only during the larval stage, which is lost in adulthood. This temporary structure is characteristic of chordates during at least some stage of their development.
Q35. The presence of a cranium is a characteristic feature of which group of chordates?
a) Urochordata
b) Cephalochordata
c) Vertebrata
d) Hemichordata
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Correct Answer: c) Vertebrata
Explanation: Vertebrates, within the subphylum Vertebrata, possess a cranium, which is a bony or cartilaginous structure surrounding and protecting the brain. The cranium is a key evolutionary innovation that distinguishes vertebrates from other chordates.