Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): All vertebrates are chordates but all chordates are not vertebrates. Reason (R): Notochord is replaced by the vertebral column in the adult vertebrates. In the light of the above statements, choose the most appropriate answer from the options given below:
Answer: (A) Both (A) and (R) are correct and (R) is the correct explanation of (A). In subphylum Vertebrata the embryonic notochord is later replaced by a cartilaginous or bony vertebral column, while protochordates (Urochordata, Cephalochordata) retain a notochord and never form a vertebral column.
- A.Both (A) and (R) are correct and (R) is the correct explanation of (A)✓
- B.Both (A) and (R) are correct but (R) is not the correct explanation of (A)
- C.(A) is correct but (R) is not correct
- D.(A) is not correct but (R) is correct
Correct Answer
(A) Both (A) and (R) are correct and (R) is the correct explanation of (A)
Solution & Explanation
In subphylum Vertebrata the embryonic notochord is later replaced by a cartilaginous or bony vertebral column, while protochordates (Urochordata, Cephalochordata) retain a notochord and never form a vertebral column. Hence all vertebrates are chordates but all chordates are not vertebrates, and the Reason correctly explains why the Assertion is true. NCERT Reference: Page 46, line 28