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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Q281.
Assertion (A): The mantle cavity in molluscs contains feather-like gills.
Reason (R): These gills have respiratory and excretory functions.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: A [ ]
Remark: Both A and R are true and R is the correct explanation of A. Explanation: Feather-like ctenidia in the mantle cavity serve respiration (and in some cases are involved in excretion/contact with coelomic fluids), so the reason supports the assertion.
Q282.
Assertion (A): Chordates possess a post-anal tail.
Reason (R): A post-anal tail is absent in non-chordates.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: A [ ]
Remark: Both A and R are true and R is the correct explanation of A. Explanation: A post-anal tail is a defining chordate feature absent in non-chordates.
Q283.
Assertion (A): Vertebrates have kidneys for excretion and osmoregulation.
Reason (R): They possess a ventral muscular heart with two, three, or four chambers.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: B [ ]
Remark: Both A and R are true but R is not the correct explanation of A. Explanation: Both are true vertebrate features, but the circulatory/heart condition does not explain kidney presence.
Q284.
Assertion (A): Hagfish (Myxine) belongs to the class Chondrichthyes.
Reason (R): It has a cartilaginous endoskeleton.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: D [ ]
Remark: Assertion (A) is false but R is true. Explanation: Hagfish (Myxine) is not a chondrichthyan; it is a cyclostome (Class Cyclostomata). The reason is true about cartilaginous skeletons but doesn't classify Myxine correctly.
Q285.
Assertion (A): Trygon (Sting ray) possesses a poison sting.
Reason (R): It belongs to the class Osteichthyes.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: C [ ]
Remark: A is true but R is false. Explanation: Trygon (a stingray) may possess a venomous spine, but rays are cartilaginous fishes (Class Chondrichthyes), not Osteichthyes.
Q286.
Assertion (A): The skin of Osteichthyes is covered with cycloid or ctenoid scales.
Reason (R): The skin of Chondrichthyes is covered with placoid scales.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: B [ ]
Remark: Both A and R are true but R is not the correct explanation of A. Explanation: Both statements correctly describe scale types in bony and cartilaginous fishes; one does not explain the other.
Q287.
Assertion (A): In amphibians, a tympanum represents the ear.
Reason (R): They do not have external ear openings like reptiles.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: B [ ]
Remark: Both A and R are true but R is not the correct explanation of A. Explanation: Amphibians have tympanic membranes (tympana) for hearing; some amphibians lack external pinnae but the presence/absence of external ears varies and the reason does not fully explain the assertion.
Q288.
Assertion (A): The hind limbs of birds are modified for various functions like walking, swimming, or clasping.
Reason (R): The forelimbs of birds are modified into wings.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: B [ ]
Remark: Both A and R are true but R is not the correct explanation of A. Explanation: Both statements describe different limb adaptations in birds; forelimb modification into wings is separate from hind limb specialization..
Q289.
Assertion (A): All viviparous animals are mammals.
Reason (R): Some sharks are viviparous.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: D [ ]
Remark: Assertion (A) is false but R is true. Explanation: Viviparity occurs outside mammals as well — e.g., some sharks — so the assertion is false; the reason provides a correct counterexample.
Q290.
Assertion (A): All triploblastic animals are coelomates.
Reason (R): Platyhelminthes are triploblastic but acoelomate.
[Animal-Kingdom] [class-xi]
a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
c) Assertion (A) is true but Reason (R) is false.
d) Assertion (A) is false but Reason (R) is true.
Correct Option: D [ ]
Remark: Assertion (A) is false but R is true. Explanation: Not all triploblastic animals have a true coelom — platyhelminths are triploblastic acoelomates, demonstrating the assertion is false.
