Try each question on your own first. Use the Show Answer button only after you have selected your option, then read the explanation and revise the related concept from your chapter notes.
1. Animals are classified based on characteristics such as
A. Level of organisation, symmetry, germ layers, and coelom
B. Only their colour and size
C. Only their geographical distribution
D. Only their diet
Answer: A. Level of organisation, symmetry, germ layers, and coelom
Explanation: Animal classification relies on fundamental features like level of organisation (cellular, tissue, organ), body symmetry, number of germ layers, and presence or absence of a coelom (body cavity).
2. Sponges (Phylum Porifera) exhibit which level of body organisation?
A. Cellular level of organisation
B. Tissue level of organisation
C. Organ level of organisation
D. Organ system level of organisation
Answer: A. Cellular level of organisation
Explanation: In sponges, cells are loosely arranged without forming true tissues, so they exhibit a cellular level of organisation, where cells perform functions individually but show some division of labour.
3. Animals like Hydra and jellyfish (Phylum Cnidaria) show which type of body symmetry?
A. Radial symmetry
B. Bilateral symmetry
C. Asymmetry
D. Spherical symmetry only
Answer: A. Radial symmetry
Explanation: Cnidarians like Hydra and jellyfish exhibit radial symmetry, where any plane passing through the central axis divides the body into two identical (mirror-image) halves.
4. In animals with bilateral symmetry, the body can be divided into identical left and right halves by
A. Only one plane passing through the centre
B. Any plane passing through the centre
C. No plane at all
D. At least four different planes
Answer: A. Only one plane passing through the centre
Explanation: Bilateral symmetry means that only a single specific plane, passing through the centre of the body along its length, can divide the organism into two identical, mirror-image halves.
5. Diploblastic animals, such as those in Phylum Cnidaria, develop from
A. Two embryonic germ layers (ectoderm and endoderm)
B. Three embryonic germ layers
C. A single embryonic germ layer
D. No distinct germ layers
Answer: A. Two embryonic germ layers (ectoderm and endoderm)
Explanation: Diploblastic animals, like cnidarians, develop from only two primary germ layers, an outer ectoderm and an inner endoderm, with an undifferentiated mesoglea between them.
6. Triploblastic animals develop from
A. Three embryonic germ layers (ectoderm, mesoderm, endoderm)
B. Only two germ layers
C. A single germ layer
D. No germ layers at all
Answer: A. Three embryonic germ layers (ectoderm, mesoderm, endoderm)
Explanation: Triploblastic animals, which include most animal phyla from Platyhelminthes onward, develop from three primary germ layers: ectoderm, mesoderm, and endoderm, giving rise to distinct organs and tissues.
7. A body cavity that is completely lined by mesoderm is called a
A. True coelom (eucoelom)
B. Pseudocoelom
C. Acoelomate condition
D. Blastocoel
Answer: A. True coelom (eucoelom)
Explanation: A true coelom is a body cavity that is completely lined by mesoderm on both the outer (body wall) and inner (gut) sides, as seen in animals like annelids and higher phyla.
8. Animals such as roundworms (Phylum Aschelminthes/Nematoda), where the body cavity is not completely lined by mesoderm, are termed
A. Pseudocoelomate
B. Coelomate
C. Acoelomate
D. Diploblastic
Answer: A. Pseudocoelomate
Explanation: In pseudocoelomate animals like roundworms, the body cavity is present but not completely lined by mesoderm, so it is referred to as a false body cavity (pseudocoelom).
9. Flatworms (Phylum Platyhelminthes), such as tapeworms, lack a body cavity altogether and are termed
A. Acoelomate
B. Coelomate
C. Pseudocoelomate
D. Diploblastic
Answer: A. Acoelomate
Explanation: Flatworms, classified under Platyhelminthes, have solid bodies without any body cavity between the body wall and the gut, making them acoelomate animals.
10. Segmentation, where the body is externally and internally divided into repeated similar units, is a distinctive feature of Phylum
A. Annelida
B. Porifera
C. Cnidaria
D. Platyhelminthes
Answer: A. Annelida
Explanation: Metameric segmentation, dividing the body into a series of similar repeating segments, is a defining feature of Phylum Annelida, seen in animals like earthworms.
11. Phylum Arthropoda is characterized by animals having
A. Jointed appendages and an exoskeleton made of chitin
B. Soft, unsegmented bodies with no appendages
C. A completely fluid-filled body with no skeleton
D. Radial symmetry only
Answer: A. Jointed appendages and an exoskeleton made of chitin
Explanation: Arthropods, the largest animal phylum, possess jointed legs (the name means "jointed feet") and a hard external skeleton made of chitin, providing protection and support.
12. Which of the following is NOT an example of an arthropod?
A. Earthworm
B. Cockroach
C. Spider
D. Prawn
Answer: A. Earthworm
Explanation: The earthworm belongs to Phylum Annelida, not Arthropoda; it lacks jointed appendages and a chitinous exoskeleton, unlike cockroaches, spiders, and prawns which are true arthropods.
13. Phylum Mollusca is characterized by animals having a soft body often covered by
A. A calcareous shell
B. A chitinous exoskeleton
C. Jointed appendages
D. Feathers
Answer: A. A calcareous shell
Explanation: Molluscs, such as snails and mussels, typically have a soft, unsegmented body that is often protected by an external calcareous shell.
14. The muscular structure used for locomotion in most molluscs is called the
A. Foot
B. Mantle
C. Radula
D. Siphon
Answer: A. Foot
Explanation: The molluscan foot is a strong muscular organ, ventrally located, primarily used for locomotion, such as in snails crawling.
15. Phylum Echinodermata is characterized by animals with
A. A spiny skin and a unique water vascular system
B. A soft body with a calcareous shell
C. Jointed appendages and an exoskeleton
D. Complete absence of a skeleton
Answer: A. A spiny skin and a unique water vascular system
Explanation: Echinoderms, like starfish and sea urchins, have a spiny, calcareous endoskeleton and a distinctive water vascular system that aids in locomotion, feeding, and respiration.
16. Starfish exhibit which type of symmetry as adults, despite having bilaterally symmetrical larvae?
A. Radial symmetry
B. Bilateral symmetry
C. Asymmetry
D. Spiral symmetry
Answer: A. Radial symmetry
Explanation: Adult echinoderms like starfish typically exhibit pentaradial (five-part radial) symmetry, though their larvae are bilaterally symmetrical, reflecting their evolutionary origin.
17. The defining feature of Phylum Chordata, present at some stage of development, is the presence of a
A. Notochord
B. Exoskeleton
C. Radula
D. Water vascular system
Answer: A. Notochord
Explanation: All chordates possess a notochord, a flexible rod-like structure providing skeletal support, at least during some stage of their embryonic development.
18. Along with a notochord, chordates are also characterized by having
A. A dorsal, hollow nerve cord and paired pharyngeal gill slits
B. A ventral, solid nerve cord only
C. No nervous system at all
D. A shell covering the entire body
Answer: A. A dorsal, hollow nerve cord and paired pharyngeal gill slits
Explanation: In addition to a notochord, chordates share other defining features: a dorsal, tubular (hollow) nerve cord, and paired pharyngeal gill slits at some point in their life cycle.
19. The subphylum Vertebrata, within Chordata, is characterized by the presence of a
A. Vertebral column (backbone) replacing the notochord in adults
B. Complete absence of any internal skeleton
C. Exoskeleton made of chitin
D. Radial symmetry
Answer: A. Vertebral column (backbone) replacing the notochord in adults
Explanation: Vertebrates are chordates in which the notochord present in the embryo is replaced by a bony or cartilaginous vertebral column in the adult, providing central support to the body.
20. Fish belong to which class of vertebrates and typically respire using
A. Pisces; gills
B. Amphibia; lungs only
C. Aves; lungs and air sacs
D. Reptilia; skin only
Answer: A. Pisces; gills
Explanation: Fish, classified under Pisces, are aquatic vertebrates that primarily respire using gills to extract dissolved oxygen from water.
21. Amphibians, such as frogs, are characterized by having a life cycle that typically involves
A. An aquatic larval stage and a terrestrial adult stage
B. A fully aquatic life throughout, with gills always present
C. A fully terrestrial life with no need for water at any stage
D. No larval stage at all
Answer: A. An aquatic larval stage and a terrestrial adult stage
Explanation: Amphibians, meaning "dual life," typically have an aquatic larval stage (like tadpoles, breathing via gills) that later metamorphoses into a terrestrial or semi-terrestrial adult stage, often breathing via lungs and skin.
22. Reptiles are distinguished from amphibians mainly by having
A. Dry, scaly skin that reduces water loss, allowing full terrestrial life
B. Moist, glandular skin requiring constant water contact
C. Gills throughout their adult life
D. Feathers covering their entire body
Answer: A. Dry, scaly skin that reduces water loss, allowing full terrestrial life
Explanation: Unlike the moist, permeable skin of amphibians, reptiles have dry, scaly skin that prevents excessive water loss, enabling them to live fully on land without depending on water for basic survival.
23. Class Aves (birds) is uniquely characterized among vertebrates by the presence of
A. Feathers
B. Gills
C. Scales made of chitin
D. A water vascular system
Answer: A. Feathers
Explanation: Feathers are a defining feature unique to birds (Class Aves) among all vertebrates, providing insulation and enabling flight in most species.
24. Which of the following is a defining characteristic of Class Mammalia?
A. Presence of mammary glands for producing milk to nourish young
B. Presence of feathers
C. Cold-blooded (ectothermic) body temperature regulation in all members
D. Exclusive reproduction by laying eggs in all members
Answer: A. Presence of mammary glands for producing milk to nourish young
Explanation: The defining feature of mammals is the presence of mammary glands in females, which produce milk to nourish their young after birth; most mammals also have hair and are warm-blooded.
25. Which of the following animals is an exception among mammals, as it lays eggs instead of giving birth to live young?
A. Platypus
B. Kangaroo
C. Elephant
D. Whale
Answer: A. Platypus
Explanation: The platypus is an egg-laying mammal (monotreme), an exception to the typical mammalian reproductive pattern of giving birth to live young, yet it still nurses its offspring with milk after hatching.
26. Warm-blooded (endothermic) animals are able to maintain
A. A relatively constant internal body temperature regardless of external conditions
B. A body temperature that always matches the surrounding environment
C. No body temperature at all
D. A body temperature only when exposed to sunlight
Answer: A. A relatively constant internal body temperature regardless of external conditions
Explanation: Endothermic (warm-blooded) animals, such as birds and mammals, can regulate their internal body temperature internally, keeping it relatively stable even when the external environment's temperature fluctuates.
27. Cold-blooded (ectothermic) animals, such as reptiles and fish, regulate their body temperature mainly by
A. Depending on external environmental sources of heat
B. Internal metabolic heat generation alone
C. Sweating profusely
D. Having feathers for insulation
Answer: A. Depending on external environmental sources of heat
Explanation: Ectothermic animals cannot generate significant internal body heat, so their body temperature largely depends on and fluctuates with the surrounding external environment, such as reptiles basking in the sun.
28. Why is Phylum Porifera (sponges) considered structurally one of the simplest animal phyla?
A. They exhibit a cellular level of organisation without true tissues or organs
B. They possess a fully developed nervous and circulatory system
C. They have jointed appendages like arthropods
D. They have a notochord like chordates
Answer: A. They exhibit a cellular level of organisation without true tissues or organs
Explanation: Sponges lack true tissues, organs, and organ systems, with cells performing functions relatively independently, making Porifera one of the structurally simplest and most primitive animal phyla.
29. Why do earthworms (Annelida), despite lacking a rigid internal skeleton, maintain body shape and enable movement effectively?
A. Their segmented body with fluid-filled coelom acts as a hydrostatic skeleton, aided by circular and longitudinal muscles
B. They possess a hard external shell like molluscs
C. They have jointed appendages like arthropods
D. Their body is completely rigid and cannot bend at all
Answer: A. Their segmented body with fluid-filled coelom acts as a hydrostatic skeleton, aided by circular and longitudinal muscles
Explanation: The fluid-filled coelom in each segment of an earthworm functions as a hydrostatic skeleton, and coordinated contraction of circular and longitudinal muscles allows the worm to change shape and move efficiently through soil.
30. Which of the following correctly represents an evolutionary trend seen across the animal kingdom, from simpler to more complex phyla?
A. Increasing complexity in body organisation, symmetry, and organ system development
B. A steady decrease in body complexity over evolutionary time
C. Complete loss of symmetry in advanced phyla
D. No relationship between phylum classification and body complexity
Answer: A. Increasing complexity in body organisation, symmetry, and organ system development
Explanation: Broadly, animal classification reflects an evolutionary trend of increasing complexity, moving from cellular-level organisation and radial symmetry in simpler phyla (like Porifera and Cnidaria) to well-developed organ systems and bilateral symmetry in more advanced phyla (like Chordata).
This page contains a chapter-wise objective practice set. Try the questions without checking the answer first, then use the explanation to understand the point you missed. The current page contains 30 questions, so you can practise in smaller sets when you are revising.
Quick revision tip
After the practice set, write down the question numbers you missed and revise only those concepts once more. This makes MCQ practice more useful than repeatedly attempting the same questions without reviewing mistakes.
