Q21. Animals in the phylum Echinodermata possess a unique internal structure called:
a) Notochord
b) Exoskeleton
c) Water vascular system
d) Gastrovascular cavity
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Correct Answer: c) Water vascular system
Explanation: Echinoderms possess a unique internal structure known as the water vascular system. This system consists of a network of fluid-filled canals used for locomotion, feeding, and gas exchange.
Q22. Which of the following phyla includes animals with a closed circulatory system?
a) Porifera
b) Annelida
c) Platyhelminthes
d) Cnidaria
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Correct Answer: b) Annelida
Explanation: Annelids, such as earthworms and leeches, possess a closed circulatory system, meaning blood is confined to vessels and is pumped by a muscular heart. This system allows for more efficient nutrient and gas exchange.
Q23. Which of the following phyla includes organisms with a notochord at some stage of their development?
a) Mollusca
b) Echinodermata
c) Annelida
d) Chordata
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Correct Answer: d) Chordata
Explanation: Chordates are characterized by the presence of a notochord at some stage of their development, along with other defining features such as a dorsal nerve cord and pharyngeal gill slits.
Q24. Animals in the phylum Hemichordata share characteristics with both chordates and:
a) Arthropods
b) Mollusks
c) Annelids
d) Echinoderms
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Correct Answer: d) Echinoderms
Explanation: Hemichordates share characteristics with both chordates and echinoderms. They possess a dorsal nerve cord like chordates and a body plan resembling that of some echinoderms.
Q25. Which of the following is a characteristic feature of organisms in the phylum Cnidaria?
a) Segmentation
b) A pseudocoelom
c) Radial symmetry
d) A closed circulatory system
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Correct Answer: c) Radial symmetry
Explanation: Cnidarians exhibit radial symmetry, meaning their body parts are arranged around a central axis. This symmetry allows them to capture prey from any direction and is typical of organisms like jellyfish and coral polyps.
Q26. Animals belonging to the phylum Porifera are characterized by:
a) Jointed appendages
b) Radial symmetry
c) A closed circulatory system
d) Pores and channels for water flow
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Correct Answer: d) Pores and channels for water flow
Explanation: Poriferans, or sponges, are characterized by their porous bodies with numerous channels and chambers for water flow. Water enters through small pores, flows through canals, and exits through larger openings, allowing for filter feeding and gas exchange.
Q27. The digestive system of animals in the phylum Platyhelminthes is:
a) Incomplete
b) Open
c) Closed
d) Compartmentalized
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Correct Answer: a) Incomplete
Explanation: Flatworms, or Platyhelminthes, have an incomplete digestive system, meaning they have a single opening serving as both the mouth and anus. Food enters and waste exits through this opening, simplifying the digestive process.
Q28. An exoskeleton made of chitin is a characteristic feature of organisms in which phylum?
a) Mollusca
b) Arthropoda
c) Echinodermata
d) Annelida
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Correct Answer: b) Arthropoda
Explanation: Arthropods possess an exoskeleton made of chitin, a tough polysaccharide, which provides support, protection, and attachment sites for muscles. This external skeleton must be shed periodically during growth, a process called molting.
Q29. Animals in the phylum Mollusca typically possess which of the following structures for locomotion?
a) Jointed appendages
b) Setae
c) A water vascular system
d) A muscular foot
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Correct Answer: d) A muscular foot
Explanation: Mollusks typically possess a muscular foot, which is a structure used for locomotion, attachment, and burrowing. The foot varies in shape and function among different mollusk groups, such as creeping in snails or digging in clams.
Q30. The larval stage of many cnidarians, including jellyfish, is called:
a) Planula
b) Nauplius
c) Trochophore
d) Tadpole
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Correct Answer: a) Planula
Explanation: The planula larva is a characteristic larval stage found in many cnidarians, including jellyfish and sea anemones. It is typically free-swimming and possesses an elongated, ciliated body for dispersal.
Q31. Animals in the phylum Annelida are characterized by:
a) Segmented bodies and setae
b) A radula for feeding
c) A water vascular system
d) Dorsoventrally flattened bodies
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Correct Answer: a) Segmented bodies and setae
Explanation: Annelids, such as earthworms and leeches, possess segmented bodies with distinct body segments and setae, which are bristle-like structures protruding from their bodies. Segmentation allows for greater flexibility and specialization of body parts.
Q32. Which of the following phyla includes animals with a complete digestive system?
a) Porifera
b) Cnidaria
c) Platyhelminthes
d) Annelida
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Correct Answer: d) Annelida
Explanation: Annelids possess a complete digestive system with separate mouth and anus openings. Food passes through a digestive tract consisting of regions such as the pharynx, esophagus, intestine, and anus, allowing for more efficient digestion and nutrient absorption.
Q33. Animals in the phylum Echinodermata exhibit which type of symmetry?
a) Bilateral symmetry
b) Radial symmetry
c) Asymmetry
d) Spiral symmetry
Show Answer
Correct Answer: b) Radial symmetry
Explanation: Echinoderms exhibit radial symmetry, meaning their body parts are arranged around a central axis, typically in multiples of five. This symmetry allows for equal access to the environment from all directions.
Q34. The body plan of animals in the phylum Hemichordata resembles that of:
a) Mollusks
b) Echinoderms
c) Chordates
d) Annelids
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Correct Answer: c) Chordates
Explanation: Hemichordates possess a body plan resembling that of chordates, with a dorsal nerve cord and pharyngeal gill slits. However, they lack a true vertebral column and are considered more closely related to echinoderms.
Q35. Animals in the phylum Arthropoda exhibit which type of symmetry?
a) Bilateral symmetry
b) Radial symmetry
c) Asymmetry
d) Spiral symmetry
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Correct Answer: a) Bilateral symmetry
Explanation: Arthropods exhibit bilateral symmetry, meaning their body can be divided into two mirror-image halves along a single plane. This symmetry allows for directional movement and specialization of body parts.
Q36. Which of the following is a characteristic feature of organisms in the phylum Mollusca?
a) Jointed appendages
b) A pseudocoelom
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 mantle, which is a thin tissue layer covering the visceral mass. The mantle often secretes a calcareous shell for protection and support, as seen in snails, clams, and other mollusks.
Q37. Animals in the phylum Porifera are primarily:
a) Parasites
b) Herbivores
c) Predators
d) Filter feeders
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Correct Answer: d) Filter feeders
Explanation: Poriferans, or sponges, are primarily filter feeders. They draw in water through pores in their bodies and filter out small particles of organic matter for food while expelling excess water. Sponges are sessile organisms, meaning they are anchored in place.
Q38. The body plan of animals in the phylum Platyhelminthes is characterized by:
a) Radial symmetry
b) Segmentation
c) Acoelomate body plan
d) A true coelom
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Correct Answer: c) Acoelomate body plan
Explanation: Platyhelminthes have an acoelomate body plan, meaning they lack a true body cavity (coelom) between the gut and body wall. Instead, their organs are bathed in parenchyma, a type of tissue filling the space between the gut and body wall.
Q39. Animals in the phylum Arthropoda have a segmented body divided into:
a) Head and thorax
b) Thorax and abdomen
c) Head, thorax, and abdomen
d) Head, thorax, abdomen, and tail
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Correct Answer: c) Head, thorax, and abdomen
Explanation: Arthropods have a segmented body divided into three distinct regions: the head, thorax, and abdomen. Each segment may bear specialized appendages for functions such as feeding, locomotion, and reproduction.
Q40. Animals in the phylum Mollusca exhibit which type of symmetry?
a) Bilateral symmetry
b) Radial symmetry
c) Asymmetry
d) Spiral symmetry
Show Answer
Correct Answer: a) Bilateral symmetry
Explanation: Mollusks exhibit bilateral symmetry, meaning their body can be divided into two mirror-image halves along a single plane. This symmetry allows for directional movement and organization of body parts.
Q41. The primary mode of locomotion for animals in the phylum Echinodermata is accomplished through:
a) Setae
b) Tentacles
c) Jointed appendages
d) Tube feet
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Correct Answer: d) Tube feet
Explanation: Echinoderms, such as sea stars and sea urchins, utilize tube feet for locomotion. These specialized structures are operated by a water vascular system and function by hydraulic pressure, allowing echinoderms to move and grip onto surfaces.
Q42. Animals in the phylum Hemichordata possess which of the following structures that resembles the notochord found in chordates?
a) Exoskeleton
b) Water vascular system
c) Dorsal nerve cord
d) Stomochord
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Correct Answer: d) Stomochord
Explanation: Hemichordates possess a structure called the stomochord, which resembles the notochord found in chordates. The stomochord is a dorsal tube-like structure located above the gut and serves a supportive role, although it is not considered a true notochord.
Q43. Which of the following is a characteristic feature of organisms in the phylum Cnidaria?
a) A true coelom
b) A segmented body
c) A pseudocoelom
d) Specialized stinging cells called cnidocytes
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Correct Answer: d) Specialized stinging cells called cnidocytes
Explanation: Cnidarians possess specialized stinging cells called cnidocytes, which contain nematocysts used for prey capture and defense. These cells are characteristic of cnidarians like jellyfish, sea anemones, and corals.
Q44. The body plan of animals in the phylum Annelida is characterized by:
a) Radial symmetry
b) Acoelomate body plan
c) Pseudocoelom
d) Segmentation and a true coelom
Show Answer
Correct Answer: d) Segmentation and a true coelom
Explanation: Annelids, such as earthworms and leeches, have a body plan characterized by segmentation and a true coelom. Segmentation allows for specialization of body parts, while the coelom provides space for internal organs and allows for greater complexity and efficiency.
Q45. Animals in the phylum Arthropoda exhibit which of the following respiratory structures?
a) Gills
b) Lungs
c) Tracheal tubes
d) A book lung
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Correct Answer: c) Tracheal tubes
Explanation: Arthropods, such as insects and spiders, utilize tracheal tubes for respiration. These tubes extend throughout the body and deliver oxygen directly to tissues, enabling efficient gas exchange without the need for specialized respiratory organs like lungs.
Q46. The larval stage of many mollusks, such as clams and oysters, is called:
a) Trochophore
b) Nauplius
c) Planula
d) Veliger
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Correct Answer: d) Veliger
Explanation: The veliger larva is a characteristic larval stage found in many mollusks, particularly those with a planktonic larval phase such as clams and oysters. Veligers possess a shell and a ciliated velum used for swimming and feeding.
Q47. Animals in the phylum Porifera are:
a) Hermaphrodites
b) Dioecious
c) Parthenogenetic
d) Asexual
Show Answer
Correct Answer: a) Hermaphrodites
Explanation: Poriferans, or sponges, are often hermaphroditic, meaning they possess both male and female reproductive organs. However, some species may also exhibit dioecious (separate sexes) or asexual reproduction.
Q48. Which of the following phyla includes animals with a nerve net rather than a centralized nervous system?
a) Mollusca
b) Echinodermata
c) Cnidaria
d) Platyhelminthes
Show Answer
Correct Answer: c) Cnidaria
Explanation: Cnidarians possess a nerve net, which is a decentralized network of interconnected nerve cells that coordinates basic sensory and motor functions. This nerve net allows for simple responses to stimuli but lacks the centralized organization found in higher animals.
Q49. Animals in the phylum Platyhelminthes are often characterized by:
a) A segmented body
b) A pseudocoelom
c) Cilia for locomotion
d) Flame cells for excretion
Show Answer
Correct Answer: c) Cilia for locomotion
Explanation: Platyhelminthes, or flatworms, often use cilia for locomotion. These hair-like structures beat rhythmically, allowing flatworms to glide smoothly across surfaces or through water.
Q50. Which of the following phyla includes animals with a muscular foot used for locomotion?
a) Mollusca
b) Annelida
c) Arthropoda
d) Echinodermata
Show Answer
Correct Answer: a) Mollusca
Explanation: Mollusks possess a muscular foot, which is a structure used for locomotion, attachment, and burrowing. The foot varies in shape and function among different mollusk groups, such as creeping in snails or digging in clams.