Question

Which one of the following statements is totally wrong about the occurrence of notochord, while the other three are correct?

• A. It is present only in larval tail in ascidian
• B. It is replaced by a vertebral column in adult frog
• C. It is absent throughout life in humans from the very beginning
• D. It is present throughout life in Amphioxus

Answer 1

The correct option is C It is absent throughout life in humans from the very beginning

Ascidians are tunicates that belong to the phylum Chordata. They contain notochord in their larval stage and gradually replaced by a single elongated solid nerve ganglion called cerebral ganglion.

All the vertebrates fishes, amphibians, reptiles, birds, mammals have the notochord in the developing stage but replaced by vertebral column later.

The larval stage of frog has notochord which is replaced by the vertebral column in adult front.

In humans notochord is present in foetal life.

Amphioxus is a cephalochordate which has notochord throughout its life.

So the correct option is c.