Question

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): The members of subphylum Vertebrata possess a notochord during the embryonic period; the notochord is replaced by a cartilaginous or bony vertebral column in adults.

• A. Both A and R are true but R is not the correct explanation of A.
• B. A is true but R is false.
• C. A is false but R is true.
• D. Both A and R are true and R is the correct explanation of A.

Hint:

Vertebrates have backbones (vertebral column). Some chordates don't.

Answer 1

The Correct Option is A

Vertebrates are a subphylum of Chordata. While the assertion is true, other chordate subphyla, Urochordata and Cephalochordata, are not vertebrates. The reason provided – that vertebrates develop a vertebral column replacing the notochord – is also accurate. However, this explanation does not fully account for why not all chordates are vertebrates. The defining characteristic of vertebrates is the development of a vertebral column, a feature absent in other chordates, which retain their notochord throughout life.