Question

In _______, the notochord is present only in the larval tail while in ________, it extends from head to tail region and is persistent throughout their life.
A. Cephalochordata and Urochordata
B. Urochordata and Cephalochordata
C. Vertebrata and Cephalochordata
D. Cephalochordata and Vertebrata

Solution:

Answer 1

Hint: The notochord is the distinguishing feature of the chordates and plays crucial functions in the development of vertebrates. It acts as a significant skeletal component of the growing embryo as well as a source of midline signals that design neighbouring tissues. Between the digestive tract and the nerve cord, the notochord is located and is orientated from head to tail. Because it is made of stiffer tissue, it enables the organism's skeleton to be supported.

Complete step-by-step solution:
Urochordata, Cephalochordata, and Vertebrata are the three subphyla that make up the phylum Chordata.
Due to the lack and presence of the notochord, the two groups Urochordata and Cephalochordata are distinguished.
These are the categories that are frequently referred to as protochordate. These are examples of marine creatures.
The notochord, which runs from the head to the tail area of animals belonging to the Cephalochordata group, is present.
Throughout the duration of the organism, the structure endures.
The notochord is exclusively found in the tail of Urochordata larvae.
In Cephalochordata, the notochord is a continuous structure that runs from the head to the tail.
In the adult, a cartilaginous or bony vertebral column takes the place of the notochord of Vertebrata.
Hence, option B is correct.
In Urochordata, the notochord is present only in the larval tail while in Cephalochordata, it extends from head to tail region and is persistent throughout their life.

Note: The three most frequently mentioned uses of the notochord are as a vertebral precursor, a skeletal (structural) component, and a midline tissue that sends developmental directional signals to surrounding tissue. The notochord serves as the body's principal structural support throughout the lifespan of lancelets.