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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Q251.
Assertion (A): The class name Reptilia refers to their creeping or crawling mode of locomotion.
Reason (R): Reptiles are mostly terrestrial animals.
[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 are true. The reason is a related fact but does not directly explain the etymology of Reptilia.
Q252.
Assertion (A): Most reptiles have a three-chambered heart.
Reason (R): Crocodiles, a type of reptile, have a four-chambered heart.
[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 key characteristics of reptiles. However, having modified forelimbs is a separate adaptation for flight, not an explanation for the presence of feathers.
Q253.
Assertion (A): Reptiles are poikilotherms.
Reason (R): They are able to maintain a constant body temperature.
[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: Reptiles are poikilotherms (true). The reason is false; poikilotherms cannot maintain a constant body temperature.
Q254.
Assertion (A): The most characteristic feature of Aves is the presence of feathers.
Reason (R): The forelimbs in 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 are true. However, the presence of modified forelimbs (wings) does not explain the origin of feathers.
Q255.
Assertion (A): The long bones of birds are hollow with air cavities (pneumatic).
Reason (R): A pneumatic endoskeleton helps in making the body light for flight.
[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: The hollow, air-filled (pneumatic) nature of bird bones is a crucial adaptation to reduce body weight, which is essential for flight.
Q256.
Assertion (A): The most unique mammalian characteristic is the presence of mammary glands.
Reason (R): Mammary glands are used to nourish the young ones.
[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: Mammary glands are considered the most unique mammalian trait because their function—producing milk to nourish young—is exclusive to this class.
Q257.
Assertion (A): All mammals are viviparous.
Reason (R): The platypus (Ornithorhynchus) is an oviparous mammal.
[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: Assertion is false because there are oviparous (egg-laying) mammals. The reason is true; the platypus is a well-known example of an exception to the general rule of viviparity in mammals.
Q258.
Assertion (A): The skin of mammals is unique in possessing hair.
Reason (R): Mammals are homoiothermous and have a four-chambered heart.
[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: Assertion is correct. The reason is false; the most unique mammalian characteristic is the presence of mammary glands (and hair is a typical mammalian feature), but homoiothermy and four-chambered heart do not explain hair presence.
Q259.
Assertion (A): Phylum Annelida is the first phylum to exhibit segmentation.
Reason (R): The body of annelids is distinctly marked out into segments or metameres.
[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: Annelids are considered the first phylum to show true segmentation; the body is distinctly metameric.
Q260.
Assertion (A): Coelenterates have a central gastro-vascular cavity.
Reason (R): It has two openings, a mouth and an anus.
[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: Coelenterates possess a gastrovascular cavity; it is incomplete and has a single opening (mouth) serving also as the anus, not two openings.
