Question

Which one of the following is not a characteristic feature of the subphylum Vertebrata?
(a)Dorsal tubular nerve cord
(b)Ventral muscular heart
(c)Presence of notochord in the adult
(d)Presence of kidneys
(e)Two pairs of lateral appendages fins or limbs

Answer 1

Hint Vertebrates, as the name implies, are the chordates with vertebral column or back home in the adult. The backbone of vertebrates protects the dorsal tubular nerve cord and serves as the axis of the internal skeleton.

Complete answer:
In vertebrates, the notochord is only embryonic, and in adults, it gets partially or completely replaced by the vertebral column. In vertebrates there is a high degree of cephalization or the formation of a distinct head region. It involves the fusion of several anterior segments, associated with the concentration of nerve cells and sense organs. The Head region accommodates the brain and sense organs. The nervous system is highly developed. There is a complex brain, enclosed within a skeletal casket called the cranium. Sense organs are well developed and sensory perception is very high.

Additional information:
-Circulatory system is a closed type. The heart is chambered, valvular, and myogenic. Blood vessels are tubular and blood is red-colored.
-The liver and pancreas are large, they develop as outgrown from the gut. The liver is an important metabolic center and meeting point of metabolic pathways.
-Vertebrate excretory organs are mesodermal kidneys. They are tubular glands, formed of mesodermal renal tubules, provided with a discharging duct.

So, the correct answer is 'Presence of the notochord in adults'.

Note:
-Nervechordbis dorsal, tubular unpaired, and Jon-ganglionated. Pharyngeal Gill slits are present throughout life in some, and only in embryonic others.
-The heart is ventral to the alimentary canal. A closed type of blood vascular system is present. Chambered ventral heart, located below the alimentary canal.
-Blood flows forward ventrally and backward dorsally. Hemoglobin is located in red blood cells.