Question

Vertebral column is derived from which of the following structures?
A. Notochord
B. Dorsal nerve cord
C. Ventral nerve cord
D. Outgrowth of cranium

Answer 1

Hint:-Vertebral column is the bony endoskeleton surrounding and protecting the spinal cord in vertebrates. The vertebral column is the backbone and the axial support of the body. Animals bearing vertebral columns are classified under subphylum Vertebrata. It consists of different types of bones which give it the ability to move.

Complete Answer:-
The vertebral column is derived from notochord or Chorda dorsalis. Animals having notochord either in their early developmental stage or throughout life are called chordates. The notochord is a rod-like supportive structure situated immediately below the nerve cord and above the alimentary canal. The notochord is made up of special vacuolated cells that are filled with semi-fluid substance.
The cells are turgid, which give the notochord its stiff nature. The notochord cells are covered by the notochordal sheath. Notochord acts as the primitive internal skeleton and a rigid axis. It also allows the movement of the body. The notochord present in the embryonic stage is replaced partially or fully by the vertebral column in the adult.
Dorsal tubular nerve cord is seen in chordates which extends along the anterior-posterior axis of their body. It is located above the alimentary canal. It encloses a cavity called neurocoel. In higher animals like humans, the anterior region of the nerve cord becomes the brain and the remaining part gets modified into the spinal cord.
Ventral nerve cord is a solid ganglionated nerve cord present in non-chordates which is entirely different from the dorsal tubular nerve cord seen in chordates. Cranium is the endoskeleton also known as braincase which encloses the brain.

The correct answer is Notochord, option (A).

Note:- Notochord or Chorda dorsalis, dorsal tubular nerve cord and pharyngeal gill slits are the three unique features that distinguish chordates from non-chordates. The body of vertebrates has paired appendages and an internal supporting skeletal framework. Muscles attached to the skeleton helps in locomotion and movement of body parts.