Given below are two statements : one is labelled as Assertion (A) and...
Assertion (A): All vertebrates are chordates but all chordates are not vertebrates.
Reason (R): Notochord is replaced by vertebral column in adult vertebrates.
The given assertion and reason are both correct, and the reason is the correct explanation of the assertion.
Explanation:
Chordates: Chordates are a group of animals that possess a notochord at some stage of their life cycle. The notochord is a flexible, rod-like structure that provides support to the body. Chordates also have a dorsal hollow nerve cord and pharyngeal slits or pouches.
Vertebrates: Vertebrates are a subcategory of chordates that have a vertebral column or backbone. The vertebral column replaces the notochord during development and provides structural support and protection for the spinal cord.
Explanation of the Assertion (A): The assertion states that all vertebrates are chordates but all chordates are not vertebrates. This is true because vertebrates are a specific subgroup of chordates that possess a vertebral column. All vertebrates have a notochord at some stage of their life cycle, but it is subsequently replaced by the vertebral column in adult vertebrates.
Explanation of the Reason (R): The reason provided in the statement is that the notochord is replaced by the vertebral column in adult vertebrates. This is also true. During embryonic development, the notochord forms as a temporary structure and provides support to the developing embryo. As the embryo matures into an adult vertebrate, the notochord is gradually replaced by the vertebral column, which becomes the main structural element of the organism.
Conclusion: Both the assertion and reason are correct, and the reason is a correct explanation of the assertion. Therefore, the correct answer is option (b) - Both (A) and (R) are correct, and (R) is the correct explanation of (A).
Given below are two statements : one is labelled as Assertion (A) and...
. Option (2) is the correct answer because all chordates are divided into three subphyla – Urochordata, Cephalochordata and Vertebrata. In subphylum Vertebrata, notochord is replaced by bony or cartilaginous vertebral column in adults. Therefore, all vertebrates are chordates but all chordates are not vertebrates.
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