Question

A notochord is present in the embryonic stage of:

• A. Some chordates
• B. All chordates
• C. All vertebrates
• D. Some vertebrates

Answer 1

Answer: (B)

All chordates

A notochord is a rod-like structure that occurs in the embryonic stage of all chordates. In urochordates, the notochord is present in the embryonic stage while in cephalochordates, the notochord extends from head to tail
and is persistent throughout their life. In the vertebrates, the notochord is present in the embryonic stage but is replaced later by a cartilaginous or bony vertebral column.

So, the correct answer is B.