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.
Option C Humans are mammals which are chordates. Phylum chordata includes animals which possess a notochord either throughout or during early embryonic life. In Ascidia (urochordata), notochord is present only in larval tail while in Amphioxus (cephalochordata), it extends from head to tail region and is persistent throughout their life. It is replaced by a vertebral column in adult frog.
