Question

Respiratory tree occurs in
(A) Sea Fan.
(B) Sea Lily.
(C) Sea Cucumber.
(D) Sea Urchin

Answer 1

Hint:--Respiratory tree is the branches of cloaca just inside the anus with the help of this they breathe by drawing water through the anus and then expelled. Respiratory tree is one of the parts of the water vascular system of echinoderms,helping in respiration. The water-vascular system consists of a perforated plate called madreporite the pores of which allowed the seawater to enter into the system.

Complete answer:
The tree contain Series of narrow tubules branching from a common duct, and lies on either side of the digestive tract. Gas exchange occurs across the thin walls of the tubules, to and from the fluid of the main body cavity.
Sea fish,sea lily,sea urchin,sea cucumber and sea urchin all are the example of phylum echinodermata.There are 5 classes of echinoderms. class of echinoderms is (1) Asteroidea(star fish). (2)Ophiuroidea(brittle star).(3) Echinoidea-sea urchin (4)Crinoidea-sea lily.(5)holothuroidea(sea cucumber).Unique feature of this phylum is the presence of water vascular system , this vascular system help in locomotion, capture and transport of food and respiration.For respiration tube feet also serve as the equivalent of gills during respiration.The thin wall of tube help in the respiratory exchange of gases. They absorb oxygen from water and pour carbon dioxide in it.
Holothuroidea is one of the classes of echinoderms which exhibit respiratory trees. Example of this class is sea cucumber.

So the correct answer is (C).

Note:- Respiratory tree and bronchial tree also present in human being but this is totally different.Terminal bronchioles divides to form respiratory bronchioles and branches of respiratory bronchioles makes respiratory branches of primary bronchioles up to terminal bronchioles makes bronchial tree.Gaseous exchange occurs in respiratory tree while these are absent in bronchial tree.