Practice MCQs, Assertion–Reason, Match List and Fill in the Blanks from NCERT Class XI Animal Kingdom — answers & concise explanations.
Animal Kingdom - Class-XI: Practice ( MCQs, Assertion-Reason, Match List-I with List-II and Fill in the Blanks) for CBSE and NEET preparation 2026.
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Q21.
The name Cnidaria is derived from the presence of:
[Animal-Kingdom] [class-xi]
Comb plates
Flame cells
Cnidoblasts or cnidocytes
Parapodia
Correct Option: C [ Cnidoblasts or cnidocytes ]
Remark: Explanation: The name Cnidaria is derived from the presence of specialized stinging cells called cnidoblasts or cnidocytes.
Q22.
Which of the following is NOT a function of cnidoblasts?
[Animal-Kingdom] [class-xi]
Anchorage
Defense
Capture of prey
Digestion
Correct Option: D [ Digestion ]
Remark: Explanation: Cnidoblasts are used for anchorage, defense, and the capture of prey. Digestion in cnidarians is extracellular and intracellular.
Q23.
The two basic body forms in cnidarians, such as the sessile, cylindrical form and the umbrella-shaped, free-swimming form, are called:
[Animal-Kingdom] [class-xi]
Larva and adult
Polyp and medusa
Ostia and osculum
Head and trunk
Correct Option: B [ Polyp and medusa ]
Remark: Explanation: Cnidarians exhibit two basic body forms: the polyp, which is sessile and cylindrical, and the medusa, which is umbrella-shaped and free-swimming.
Q24.
The alternation of generations seen in cnidarians like Obelia is called:
[Animal-Kingdom] [class-xi]
Metamerism
Metamorphosis
Metagenesis
Parthenogenesis
Correct Option: C [ Metagenesis ]
Remark: Explanation: Cnidarians that exist in both polyp and medusa forms exhibit an alternation of generations called Metagenesis.
Q25.
Ctenophores are commonly known as:
[Animal-Kingdom] [class-xi]
Sea anemones
Sea walnuts or comb jellies
Bath sponges
Tapeworms
Correct Option: B [ Sea walnuts or comb jellies ]
Remark: Explanation: Ctenophores are commonly known as sea walnuts or comb jellies.
Q26.
Locomotion in ctenophores is carried out by:
[Animal-Kingdom] [class-xi]
Tentacles
Parapodia
Eight external rows of ciliated comb plates
Muscular foot
Correct Option: C [ Eight external rows of ciliated comb plates ]
Remark: Explanation: The body of a ctenophore bears eight external rows of ciliated comb plates, which help in locomotion.
Q27.
The property of a living organism to emit light, which is well-marked in ctenophores, is known as:
[Animal-Kingdom] [class-xi]
Fluorescence
Phosphorescence
Bioluminescence
Chemiluminescence
Correct Option: C [ Bioluminescence ]
Remark: Explanation: Bioluminescence, the property of a living organism to emit light, is a well-marked characteristic of ctenophores.
Q28.
The specialized cells that help in osmoregulation and excretion in Platyhelminthes are called:
[Animal-Kingdom] [class-xi]
Flame cells
Cnidoblasts
Nephridia
Malpighian tubules
Correct Option: A [ Flame cells ]
Remark: Explanation: In Platyhelminthes (flatworms), specialized cells called flame cells help in osmoregulation and excretion.
Q29.
Platyhelminthes are described as:
[Animal-Kingdom] [class-xi]
Radially symmetrical and diploblastic
Bilaterally symmetrical and acoelomate
Asymmetrical and coelomate
Bilaterally symmetrical and pseudocoelomate
Correct Option: B [ Bilaterally symmetrical and acoelomate ]
Remark: Explanation: Flatworms (Platyhelminthes) are bilaterally symmetrical, triploblastic, and acoelomate animals.
Q30.
The body of Aschelminthes is circular in cross-section, hence they are called:
[Animal-Kingdom] [class-xi]
Flatworms
Segmented worms
Roundworms
Spiny-bodied animals
Correct Option: C [ Roundworms ]
Remark: Explanation: Aschelminthes have a body that is circular in cross-section, which is why they are called roundworms.
