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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Q231.
Assertion (A): The most distinctive feature of echinoderms is the water vascular system.
Reason (R): The water vascular system helps in locomotion, food capture, and respiration.
[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 water vascular system is unique to echinoderms and is crucial for several key life functions, including locomotion, feeding, and respiration.
Q232.
Assertion (A): Adult echinoderms are radially symmetrical, but their larvae are bilaterally symmetrical.
Reason (R): All echinoderms are exclusively marine.
[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 correct facts about echinoderms. However, their marine habitat does not explain their change in symmetry during development.
Q233.
Assertion (A): An excretory system is absent in echinoderms.
Reason (R): In echinoderms, the digestive system is incomplete.
[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; echinoderms lack a specialized excretory system. The reason is false; their digestive system is complete, with a mouth and an anus.
Q234.
Assertion (A): Hemichordata is now placed as a separate phylum under non-chordata.
Reason (R): Hemichordates have a rudimentary structure called a stomochord, which is similar to a notochord.
[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. Hemichordata was moved out of Chordata, and it possesses a stomochord. However, the presence of a stomochord was the reason it was previously included in Chordata; its reclassification is due to understanding that the stomochord is not homologous to the notochord.
Q235.
Assertion (A): Chordates are characterized by a dorsal, hollow nerve cord.
Reason (R): Non-chordates have a ventral, solid, and double central nervous system.
[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 the nervous systems of chordates and non-chordates, respectively. However, the state of the non-chordate nervous system is a point of contrast, not an explanation for the chordate condition.
Q236.
Assertion (A): All vertebrates are chordates, but all chordates are not vertebrates.
Reason (R): In vertebrates, the notochord is replaced by a vertebral column in the adult, which is not true for protochordates.
[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: This statement is justified because all vertebrates possess a notochord at some stage (making them chordates), but protochordates are chordates that never develop a vertebral column (so not all chordates are vertebrates).
Q237.
Assertion (A): Urochordata and Cephalochordata are referred to as protochordates.
Reason (R): In Urochordata, the notochord is present only in the larval tail.
[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 describes a key feature of Urochordata, but it doesn't explain why both subphyla are grouped as protochordates.
Q238.
Assertion (A): In Cephalochordata, the notochord is persistent throughout life.
Reason (R): It extends from the head to the tail region.
[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 persistence of the notochord throughout life and its extension from head to tail are the defining characteristics of the subphylum Cephalochordata.
Q239.
Assertion (A): Cyclostomes are ectoparasites on some fishes.
Reason (R): They have a sucking and circular mouth without jaws.
[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 sucking, circular, jawless mouth of cyclostomes is an adaptation for their ectoparasitic lifestyle on other fish.
Q240.
Assertion (A): Cyclostomes die after spawning.
Reason (R): They are marine but migrate to fresh water for spawning.
[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 facts about the life cycle of cyclostomes. However, their migration to freshwater for spawning doesn't explain why they die afterward.
