Question

Excretory function in Ascidia is performed by
a. Dorsal tubercle
b. Neural gland
c. Endostyle
d. Dorsal lamina

Answer 1

Ascidia is simply a marine tunicate. A well grown excretory system is not present in Ascidia. Nephrocytes are found in the blood accumulated excretory products in the cytoplasm of a plant. Neural glands have also been considered to perform excretory functions in Ascidia.

Complete answer:

Option A – Dorsal tubercle also known as Lister's tubercle is a bony prominence situated in the distal end of the radius, it is palpable on the dorsum of the wrist. Dorsal tubercle serves as a pulley for the tendon of extensor pollicis longus that wraps around the medial side as well as takes a 45 degree turn.

Option B – Neural gland is s glandular mass in ascidians that is found in close relation to the nerve ganglion as well as it is possibly homologous with the pituitary body of vertebrates. The neural gland is a complex of Ascidia interrupt including three main parts: dorsal tubercle, ciliated duct, as well as neural gland.

Option C – Endostyle is a pair of parallel longitudinal folds projecting into the pharyngeal cavity in lower chordates similar to the tunicates. They secrete mucus for trapping food particles in the body.

Option D – Dorsal lamina is a longitudinal membrane found in tunicates that projects into the cavity of a branchial sac as well as it is borne by the large median dorsal blood vessel also known as the vessel itself.

Hence, the correct answer is option (B).

Note: Small particulates along with large macromolecules in Neural gland, are disposed of by the water stream by endocytosis present on neural gland cells. Large particulates deliver onto the dorsal tubercle and they do not enter the system.