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Statement (S) Lancelets are jawless prim...

Statement (S) Lancelets are jawless primitive fish like vertebrates
Statement (R) In lancelets notochord tubular nerve cord and pharyngeal gill slits are present the throughout their life

A

S is correct but R is wrong

B

S is wrong but R is correct

C

Both S and R are correct and R is correct explanation of S

D

Both S and R are correct but R is not correct explanation of S

Text Solution

Verified by Experts

The correct Answer is:
B
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The statements given below highlight some of the chordates features. They have a hollow nervous system which is present ventrally above the notochord. II. They prossess four pharyngeal gill slits present in the from of perfortions on the lateral sides of pharynx. III. Epidermis is made up of stratified epithelium. IV. They have two pairs of appendages, one pair at the begnning of the trunk and other in the middle of the trunk. V. They have a closed vascular system.

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Which of the following statements is correct for the phylum whose organisms are characterized by the presence of a dorsal hollow nerve cord and paired pharyngeal gill slits ?

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Statement-1 : Cephalochordata bears notochord all along the body throughout life Statement-2 Urochordate bears vertebral column only in tail region throughout the life Then which is correct?

Select the option with a correct representation of an animal belonging to the below mentioned class of vertebrates. I. The notochord is persisitent throughout life. The mouth is ventral. II. The skin is moist without scales . The tail may be present. III. 6 to 15 pairs of gill slits. Jaws absent. IV. Viviparous usually. pinna present in most of the members.

Indicate whether the following statements are true or false : (i) Fish heart contains only oxygenated blood. (ii) Closure of A-V valves produces the second heart sound. (iii) The vagus nerve retards the heart rate. (iv) The S-A node is the pacemaker of the heart. (v) Columnae carneae occur in the auricles. (vi) Purkinje fibres are nerve fibres present in the heart wall.

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