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 vertebrate.
Reason (R) : The members of subphylum vertebrata possess notochord during the embryonic period, the notochord is replaced by cartilaginous or bony vertebral column in adults.
In the light of the above statements, chocse the correct answer from the options given below:
- A
(A) is false but (R) is true
- B
Both (A) and (R) are true and (R) is the correct explanation of (A)
- C
Both (A) and (R) are true but (R) is not the correct explanation of (A)
- D
(A) is true but (R) is false
Vertebrata is a subphylum within phylum Chordata, so every vertebrate is by definition a chordate, but many chordates (e.g. urochordates, cephalochordates) never develop a vertebral column.
In vertebrates, the embryonic notochord is later replaced by a cartilaginous or bony vertebral column, which is the defining feature of the subphylum. This precisely explains why all vertebrates qualify as chordates while not all chordates qualify as vertebrates.
Hence both A and R are true, and R is the correct explanation of A.
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