CSS Zoology MCQs

This comprehensive set of MCQs on Zoology for the Central Superior Services (CSS) examination is designed to cover all essential topics outlined in the CSS syllabus. Addressing key areas such as animal classification, physiology, behavior, reproduction, and ecology, these MCQs aim to equip aspiring CSS candidates with a solid understanding of animal biology and its applications in various fields.

Who should practice CSS Zoology MCQs?

Candidates preparing for the CSS examination who wish to deepen their knowledge of animal biology, including animal anatomy, physiology, and ecology.
Individuals interested in understanding the biological and ecological aspects of the animal kingdom, which are crucial for civil services roles in environmental management and wildlife conservation.
University students focusing on high-yield topics like genetics, reproduction, and animal behavior, which are essential for the CSS Zoology syllabus.
Anyone looking to enhance their knowledge of zoology and its contributions to fields such as agriculture, medicine, conservation, and environmental science.
Students committed to mastering zoology to excel in competitive exams and pursue careers in research, wildlife management, and biodiversity conservation.

1. Which of the following is the primary characteristic of the architectural pattern of animals?

A) Symmetry
B) Exoskeleton
C) Endoskeleton
D) Respiratory system

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2. The taxonomic hierarchy in the animal kingdom begins with the:

A) Species
B) Family
C) Genus
D) Domain

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3. Which of the following is a major subdivision of the animal kingdom?

A) Fungi
B) Protista
C) Plantae
D) Archaea

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4. The Protozoa are primarily classified based on:

A) Habitat
B) Mode of reproduction
C) Locomotion
D) Feeding habits

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5. What is the primary method of locomotion in protozoa?

A) Flagella
B) Cilia
C) Pseudopodia
D) Both A and B

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6. Which of the following protozoan groups is of veterinary importance?

A) Ciliates
B) Amoebas
C) Plasmodium
D) Euglenoids

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7. Which of the following is a characteristic of the body wall in Porifera?

A) Multilayered epidermis
B) Single-layered epidermis
C) Presence of cilia
D) High degree of segmentation

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8. The skeleton of Porifera consists primarily of:

A) Calcium carbonate
B) Silica
C) Collagen fibers
D) Chitin

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9. In Coelenterates, the reproductive plan includes:

A) Hermaphroditism
B) External fertilization
C) Alternation of generations
D) Asexual reproduction only

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10. Coral reefs are primarily formed by:

A) Molluscs
B) Cnidarians
C) Arthropods
D) Echinoderms

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11. Platyhelminthes exhibit parasitic adaptations in which of the following ways?

A) Modified feeding structures
B) Specialized reproductive systems
C) Ability to regenerate lost body parts
D) All of the above

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12. Nematodes are medically important due to their:

A) Ability to cause malaria
B) Role as vectors
C) Parasitic nature, causing diseases like ascariasis
D) Role in soil health

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13. Annelids display the characteristic feature of:

A) Segmentation
B) Radial symmetry
C) Asexual reproduction
D) External fertilization

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14. The ecological importance of annelids includes:

A) Nitrogen fixation
B) Decomposition and soil aeration
C) Pollination
D) Water purification

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15. The molluscan foot is primarily modified for:

A) Locomotion
B) Feeding
C) Respiration
D) Reproduction

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16. In molluscs, the feeding structure is known as the:

A) Radula
B) Beak
C) Mandible
D) Siphon

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17. Molluscs are an important part of the shellfishery due to their:

A) High reproductive rates
B) Nutritional value
C) Ability to produce pearls
D) Slow growth

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18. Arthropods show modifications in their mouth parts primarily for:

A) Feeding
B) Communication
C) Sensory detection
D) Respiration

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19. Arthropods play a major role as vectors in the transmission of:

A) Viruses
B) Bacteria
C) Protozoans
D) All of the above

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20. The ecological importance of arthropods includes their role in:

A) Pollination
B) Decomposition
C) Soil formation
D) All of the above

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21. Echinoderms are primarily characterized by:

A) Bilateral symmetry
B) Radial symmetry
C) Presence of an exoskeleton
D) Asexual reproduction

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22. The evolutionary relationship of echinoderms to other animals is based on:

A) Their larval development
B) Their skeleton composition
C) Their nervous system
D) Their feeding mechanism

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23. Hemichordates are considered to be evolutionarily related to:

A) Chordates
B) Arthropods
C) Echinoderms
D) Annelids

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24. The evolutionary perspective of invertebrate chordates suggests that they are:

A) A direct ancestor of vertebrates
B) A separate evolutionary branch
C) Not related to vertebrates
D) The most primitive form of life

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25. Fish are adapted to aquatic life through:

A) Gills for respiration
B) Scales for protection
C) Streamlined bodies for efficient movement
D) All of the above

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26. Amphibians made the transition to land by developing:

A) Lungs for respiration
B) Legs for movement
C) Moist skin for respiration
D) All of the above

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27. The main characteristic of reptiles that distinguishes them from amphibians is:

A) External fertilization
B) Scaly skin
C) Water-based reproduction
D) Presence of a notochord

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28. Reptiles are adapted to terrestrial life through:

A) Internal fertilization
B) Amniotic eggs
C) Waterproof skin
D) All of the above

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29. Birds are adapted for flight through:

A) Light bones
B) Feathers
C) High metabolic rate
D) All of the above

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30. Migration in birds is primarily driven by:

A) Temperature regulation
B) Reproductive needs
C) Availability of food
D) All of the above

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31. Mammals are characterized by the presence of:

A) Hair or fur
B) Three-chambered heart
C) Oviparity
D) External fertilization

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32. The structural adaptation of mammals for temperature regulation includes:

A) Fur or hair
B) Sweat glands
C) Fat deposits
D) All of the above

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33. The chemical basis of animal life includes:

A) Carbohydrates, lipids, and proteins
B) Water, minerals, and vitamins
C) Nucleic acids only
D) Proteins and lipids only

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34. The central dogma of cell biology describes the flow of genetic information from:

A) DNA to RNA to protein
B) Protein to RNA to DNA
C) RNA to DNA to protein
D) DNA to protein to RNA

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35. Meiosis results in the formation of:

A) Two genetically identical cells
B) Four genetically diverse cells
C) One genetically identical cell
D) Two genetically diverse cells

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36. Mitosis results in the formation of:

A) Four genetically diverse cells
B) Two genetically identical cells
C) One genetically identical cell
D) Two genetically diverse cells

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37. Protozoa reproduce primarily by:

A) Budding
B) Binary fission
C) Spore formation
D) Fragmentation

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38. Parasitism in protozoa is often characterized by:

A) A mutualistic relationship with host
B) Harmful interaction with the host
C) Symbiotic relationship
D) Commensalism

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39. The mesozoan organisms are characterized by:

A) Simple body plan with few cells
B) Complex organ systems
C) Presence of exoskeleton
D) Bilateral symmetry

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40. The cell types of Porifera include:

A) Choanocytes, amoebocytes, and pinacocytes
B) Cnidocytes, epithelia, and sensory cells
C) Neurons, epidermal, and glandular cells
D) Muscle, epithelial, and ciliated cells

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41. The primary function of the choanocytes in Porifera is:

A) Digestion of food
B) Water filtration and capture of food particles
C) Reproduction
D) Protection from predators

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42. The most complex group of animals in terms of body structure and organization is:

A) Cnidarians
B) Arthropods
C) Molluscs
D) Vertebrates

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43. The presence of a notochord is a characteristic feature of:

A) Amphibians
B) Reptiles
C) Chordates
D) Molluscs

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44. Which of the following is NOT a characteristic of all vertebrates?

A) A dorsal nerve cord
B) A vertebral column
C) Exoskeleton
D) Bilateral symmetry

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45. In which group of animals does external fertilization primarily occur?

A) Reptiles
B) Amphibians
C) Birds
D) Fish

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46. The excretory system in vertebrates is primarily responsible for:

A) Producing offspring
B) Maintaining homeostasis
C) Circulating oxygen
D) Regulating temperature

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47. The primary function of the diaphragm in mammals is to:

A) Regulate heart rate
B) Facilitate breathing
C) Filter blood
D) Control digestion

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48. The circulatory system of mammals is:

A) Open and unidirectional
B) Open and bidirectional
C) Closed and unidirectional
D) Closed and bidirectional

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49. The term “vertebrate” refers to animals that:

A) Have an exoskeleton
B) Possess a backbone or spinal column
C) Are capable of flight
D) Live in aquatic environments

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50. Which of the following is characteristic of amphibians?

A) Lungs and skin for respiration
B) Amniotic eggs
C) Scaly skin
D) Placenta for nourishment

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51. Which of the following is the primary role of the kidneys in mammals?

A) Respiration
B) Excretion of nitrogenous waste
C) Production of hormones
D) Storage of bile

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52. The formation of milk in mammals is controlled by:

A) Testosterone
B) Estrogen
C) Prolactin
D) Oxytocin

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53. The term “amphibian” refers to animals that:

A) Live only on land
B) Live only in water
C) Live both on land and in water
D) Are capable of flight

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54. The primary method of reproduction in most molluscs is:

A) External fertilization
B) Internal fertilization
C) Parthenogenesis
D) Asexual reproduction

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55. The water vascular system in echinoderms is involved in:

A) Locomotion
B) Respiration
C) Circulation
D) All of the above

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56. Which of the following is the primary function of the gills in fish?

A) Digestion of food
B) Oxygen exchange
C) Circulation of blood
D) Waste excretion

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57. Which of the following animals exhibits bilateral symmetry?

A) Cnidarians
B) Arthropods
C) Echinoderms
D) Porifera

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58. In which group of animals does the body typically consist of three distinct layers (ectoderm, mesoderm, and endoderm)?

A) Protozoa
B) Cnidarians
C) Flatworms
D) Annelids

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59. The process of metamorphosis is primarily observed in:

A) Amphibians
B) Birds
C) Reptiles
D) Mammals

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60. The largest group of living animals, in terms of species, is:

A) Insects
B) Molluscs
C) Fish
D) Birds

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61. Which of the following is a characteristic feature of cnidarians?

A) Presence of a circulatory system
B) Radial symmetry
C) Exoskeleton
D) Bilateral symmetry

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62. The primary function of the hydrostatic skeleton in many invertebrates is:

A) Protection from predators
B) Locomotion
C) Support and structure
D) Digestion of food

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63. Which of the following is true regarding the nervous system of invertebrates?

A) It is highly developed in all invertebrates
B) It is present only in the more complex invertebrates
C) It consists of a centralized brain and spinal cord
D) It is typically decentralized and spread throughout the body

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64. What type of body cavity is found in arthropods?

A) Coelom
B) Pseudocoelom
C) No body cavity
D) Hemocoel

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65. Which group of animals is characterized by a hard exoskeleton, segmented bodies, and jointed appendages?

A) Molluscs
B) Annelids
C) Arthropods
D) Echinoderms

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66. In the life cycle of echinoderms, the adult form is usually:

A) Bilaterally symmetrical
B) Radially symmetrical
C) Asymmetrical
D) None of the above

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67. The clade that includes all animals with a true coelom is known as:

A) Protostomia
B) Deuterostomia
C) Ecdysozoa
D) Lophotrochozoa

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68. Which of the following is true about the digestive system of most molluscs?

A) They have a complete digestive system with a mouth and anus
B) They have an incomplete digestive system
C) They use intracellular digestion only
D) They do not have a digestive system

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69. Which of the following is a major difference between vertebrates and invertebrates?

A) Vertebrates have an endoskeleton, invertebrates have an exoskeleton
B) Vertebrates have a more complex nervous system
C) Vertebrates have a backbone, while invertebrates do not
D) All of the above

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70. Which of the following is the most important characteristic that defines mammals?

A) Hair or fur
B) Ability to fly
C) Amniotic eggs
D) Warm-blooded metabolism

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71. The primary function of the placenta in mammals is to:

A) Facilitate gas exchange between the mother and fetus
B) Protect the fetus from pathogens
C) Store nutrients for the fetus
D) Produce hormones to regulate the pregnancy

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72. The main function of the lymphatic system in mammals is to:

A) Transport oxygen
B) Remove waste products from cells
C) Regulate body temperature
D) Fight infections and return tissue fluid to the bloodstream

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73. The first vertebrates to colonize land were:

A) Amphibians
B) Reptiles
C) Fish
D) Birds

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74. In amphibians, the skin plays a vital role in:

A) Producing mucus for digestion
B) Absorbing oxygen and water
C) Excreting nitrogenous waste
D) Storing fat for energy

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75. The main characteristic that distinguishes reptiles from amphibians is:

A) The presence of scales
B) The presence of an amniotic egg
C) The ability to breathe through skin
D) Cold-blooded metabolism

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76. In birds, the structure responsible for the flight is the:

A) Heart
B) Beak
C) Wings
D) Feathers

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77. The heart of fish has how many chambers?

A) One
B) Two
C) Three
D) Four

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78. The primary purpose of feathers in birds is to:

A) Regulate body temperature
B) Protect against water loss
C) Facilitate flight
D) Protect the eyes

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79. Which of the following is true regarding the digestive system of carnivores?

A) They have long intestines for digestion of plant material
B) They have a large cecum for digestion of cellulose
C) They have sharp teeth and short intestines for digesting meat
D) They rely on fermentation in their stomachs to digest food

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80. The process of gas exchange in fish occurs through:

A) Gills
B) Lungs
C) Skin
D) Tracheae

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81. The major source of energy for birds during migration is:

A) Fat reserves
B) Carbohydrates from seeds
C) Proteins from insects
D) Glucose from blood circulation

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82. Which group of animals is characterized by the presence of exoskeletons made of chitin?

A) Arthropods
B) Molluscs
C) Echinoderms
D) Cnidarians

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83. Which of the following statements about amphibians is TRUE?

A) They have a completely terrestrial lifestyle
B) They reproduce exclusively through external fertilization
C) Their eggs are adapted to dry land environments
D) They have a three-chambered heart

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84. Which group of animals has evolved the most specialized and complex brain structure?

A) Invertebrates
B) Fish
C) Birds
D) Mammals

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85. The structure responsible for controlling the balance and orientation of the body in fish is the:

A) Lateral line
B) Swim bladder
C) Heart
D) Gills

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86. Which of the following is the characteristic feature of the skeleton in cartilaginous fish (Chondrichthyes)?

A) Bony endoskeleton
B) Cartilage-based skeleton
C) Absence of a skeleton
D) Exoskeleton made of chitin

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87. Which of the following animals has a closed circulatory system?

A) Molluscs
B) Arthropods
C) Fish
D) Amphibians

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88. The majority of the oxygen transport in the blood of most vertebrates is carried out by:

A) Plasma proteins
B) Hemoglobin
C) White blood cells
D) Platelets

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89. Which of the following is the primary purpose of the exoskeleton in arthropods?

A) To protect from dehydration
B) To store food
C) To protect from predators and provide structural support
D) To facilitate digestion

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90. Which of the following adaptations is found in mammals but not in reptiles?

A) Amniotic egg
B) Hair or fur
C) Internal fertilization
D) Three-chambered heart

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91. Which of the following is true about monotremes?

A) They are placental mammals
B) They lay eggs
C) They do not produce milk
D) They are found only in Africa

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92. The primary characteristic that distinguishes birds from reptiles is:

A) The presence of feathers
B) The ability to fly
C) The presence of a four-chambered heart
D) The presence of amniotic eggs

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93. Which group of animals is known for their ability to regenerate lost body parts?

A) Amphibians
B) Arthropods
C) Echinoderms
D) Birds

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94. The primary reason amphibians are restricted to moist environments is:

A) Lack of lungs
B) Need for external fertilization
C) Lack of a waterproof epidermis
D) Inability to regulate body temperature

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95. Which of the following characteristics is shared by all mammals?

A) Ability to fly
B) Ability to produce milk
C) Laying of eggs
D) External fertilization

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96. In reptiles, the structure that prevents desiccation and provides protection is the:

A) Scaly skin
B) Feathers
C) Fur
D) Hair

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97. The term “ectothermic” refers to animals that:

A) Regulate their body temperature internally
B) Depend on external heat sources to regulate body temperature
C) Are warm-blooded
D) Maintain a constant body temperature regardless of environmental conditions

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98. Which of the following is the most significant difference between amphibians and reptiles?

A) The type of fertilization
B) The presence of a backbone
C) The presence of an amniotic egg
D) The number of chambers in the heart

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99. In which of the following animals is external fertilization commonly observed?

A) Mammals
B) Birds
C) Fish
D) Reptiles

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100. The process by which some animals, such as amphibians and reptiles, regulate their body temperature is called:

A) Homeostasis
B) Thermoregulation
C) Photosynthesis
D) Metabolism

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