In the give diagram, typical chordate plan is given. Identify A and B.

In the given diagram of the typical chordate. Identify the parts labelled as $1, 2, 3, 4, 5$ and select the correct option?

Given below are two statements: one is labelled as Assertion and the other is labelled as Reason.

Assertion: All vertebrates are chordates, but all chordates are not vertebrates.

Reason: Notochord is replaced by a vertebral column in the adult vertebrates.

In the light of the above statements, choose the most appropriate answer from the options given below:

Which of the following statements are true for the phylum-Chordata?

(a) In Urochordata, notochord extends from head to tail, and it is present throughout their life.

(b) In Vertebrata, the notochord is present during the embryonic period only.

(c) Central nervous system is dorsal and hollow.

(d) Chordata is divided into 3 subphyla: Hemichordata, Tunicata, and Cephalochordata.

Name the classes of Tetrapoda that exhibit the following characters:

Select the correct statement related to chordates.

A. Presence of a mid-dorsal, solid and double nerve cord.

B. Presence of closed circulatory system.

C. Presence of paired pharyngeal gillislits.

D. Presence of dorsal heart

E. Triploblastic pseudocoelomate animals.

Choose the correct answer from the options given below:

Statement $\left(\mathrm{S}\right):$ Chordates have a tail extending posterior to the anus. It contains skeletal elements and muscles but lacks coelom and visceral organs.

Reason $\left(\mathrm{R}\right):$ In aquatic organisms, it acts as a balancing organ.

Consider following features:

• Organ system level of organisation
• Bilateral symmetry
• True coelomates with segmentation of body.

Select the correct option of animal group which possess all the above characteristics: