Question: 142. 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 a cartilaginous or bony vertebral column in adults.
In the light of the above statements, choose the correct answer from the options given below:
(1) Both \mathbf{A} and \mathbf{R} are true and \mathbf{R} is the correct explanation of \mathbf{A}
(2) Both \mathbf{A} and \mathbf{R} are true but \mathbf{R} is not the correct explanation of \mathbf{A}
(3) \mathbf{A} is true but \mathbf{R} is false
(4) \mathbf{A} is false but \mathbf{R} is true
Answer: Option (2)
Explanation:
The Assertion is true because vertebrates belong to the phylum Chordata, but Chordata also includes two non-vertebrate subphyla: Urochordata and Cephalochordata.
The Reason is also true because in vertebrates, the notochord present in the embryo is replaced by a vertebral column in adulthood.
However, the Reason does not explain why all chordates are not vertebrates. It only describes a characteristic of vertebrates.
Therefore, both statements are true but the Reason is not the correct explanation of the Assertion.