Question

The blind sac body plan is applicable to
(A)Porifera
(B)Annelida and Arthropoda
(C)Cnidaria and Platyhelminthes
(D)None of these

Answer 1

The single opening roles as both mouths for the intake of food and anus for undigested waste to excrete out such a digestive tract are known as incomplete animals having a blind sac body plan show tissue grade body organization.

Complete answer: Option A- Porifera: The easiest body plan within the phylum Porifera is the asconoid body plan. This is such a simple structure because the body plan has only one large inward chamber, called a spongocoel, that is striped with water-filtering choanocyte cells.
Option B- Annelida and Arthropoda: Annelida and Arthropoda have a segmented body plan with both circular and lengthwise muscles is the ideal structure for active burrowing. A one-way gut moves through the body, and they have both a circulatory system and nervous system.
Option C- Cnidaria and Platyhelminthes: The blind sac body plan is the body plan where there is a single slot of the digestive system. The tube-like digestive system begins with a single opening through which the food is taken inside and the digested food is removed through the same opening. The gut is lined with a single layer of endodermal cells that engulf and digest food. Cnidaria and Platyhelminthes show this type of body plan.
Thus, the correct answer is Option C, Cnidaria and Platyhelminthes

Note: Blind sac body plan is described by a digestive cavity that has a single aperture, which functions as mouth and anus. The cells are specialized and they have a division of labor. Digestion is both intracellular and extracellular.