Question

The tube within tube plan is not present in _____
(A)Taenia
(B)Pheretima
(C)Leech
(D)Ascaris

Answer 1

The cell aggregate plan is a type of body plan in which the body has a cluster or aggregation of cells which are not organized into tissues or organs. In the blind sac plan, the body has a single cavity which functions as digestive tract and coelom both.

Complete answer:
In the tube within a tube body plan there are two openings one for food to enter the body and other for wastes to leave the body example- roundworms. The tube within tube plan allows specialization of parts along the tube like stomata, intestine etc.
Tube within tube plan is the development of a fluid-filled cavity between the outer body wall and the digestive tube. This tube within tube plan is seen in acoelomate, pseudocoelomate and coelomate animals.
(1) Taenia is a genus of tapeworms that are acoelomates.
(2) Pheretima is a genus of earthworms that are true coelomates.
(3) Leeches are segmented worm like animals belonging to phylum Annelida that are schizocoelomates.
(4) Ascaris is a genus of parasitic roundworms pseudocoelomates.
(5) Leeches are segmented parasitic worms which belong to phylum Annelida. Leech does not show tube body plan.

Hence the correct answer is option(C)

Note: Leeches are closely related to the oligochaetes that include earthworm and like them have soft, muscular, segmented bodies that can contract. The majority of leeches survive in freshwater habitats while some are found in marine and terrestrial regions.