Vertebral column in a modified

Options

A. Nerve cord
B. Notochord
C. Umbilical cord
D. Spermatic cord

Answer

### Step-by-Step Solution:

1. **Definition of Vertebral Column**: The vertebral column, also known as the backbone, is a central axis of the skeleton in vertebrates. It is located on the dorsal side of the body and plays a crucial role in supporting the body structure and allowing for an upright posture.

2. **Characteristics of the Vertebral Column**: The vertebral column is a characteristic feature of vertebrates, which are animals that possess a backbone. It helps in maintaining the structural integrity of the body and aids in movement.

3. **Development of the Vertebral Column**: In vertebrates, the vertebral column originates from a structure called the notochord. The notochord is a flexible rod-like structure found in the embryonic stage of chordates.

4. **Notochord vs. Vertebral Column**: The notochord is present during the embryonic development of chordates, and as the organism matures, the notochord is replaced by the vertebral column in the adult form. This transformation signifies the modification of the notochord into a more complex structure, the vertebral column.

5. **Other Related Structures**: The transcript mentions other structures like the nerve cord, umbilical cord, and spermatic cord, but these are not directly related to the modification of the vertebral column. The focus remains on the notochord as the primary structure that modifies into the vertebral column.

6. **Conclusion**: Therefore, the vertebral column is a modified structure derived from the notochord, which is a defining characteristic of the phylum Chordata.

### Final Answer:
The vertebral column is a modified structure derived from the notochord.

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