Lower Phyla Classification & Organization — NEET Biology

Correct answer: B — S2, S3 and S5 only

The question asks to identify the statements that are NOT correct about Phylum Porifera. Let's analyze each statement: S1: "Sponges are typically sessile, predominantly marine organisms with a cellular level of organisation." This statement is correct. Sponges are generally marine and primitive multicellular animals with cellular level organization, and adult sponges are sessile. S2: "They exhibit either radial or bilateral symmetry depending on the species and are generally triploblastic." This statement is NOT correct. Sponges are mostly asymmetrical, not radially or bilaterally symmetrical. Also, they have a cellular level of organization and lack true germ layers, thus are not triploblastic (or even diploblastic in the strict sense). S3: "Digestion in Porifera is exclusively extracellular, occurring within a central gastro-vascular cavity." This statement is NOT correct. Digestion in sponges is intracellular, and they do not possess a gastro-vascular cavity. S4: "Choanocytes are unique flagellated cells that create water currents and aid in food gathering." This statement is correct. Choanocytes line the spongocoel and canals and are crucial for the water transport system and food gathering. S5: "Their body support system consists of a notochord during embryonic development and a vertebral column in adults." This statement is NOT correct. Porifera lack a notochord and vertebral column; their body is supported by a skeleton of spicules or spongin fibres. Therefore, statements S2, S3, and S5 are NOT correct. Option B correctly identifies S2, S3, and S5 as the incorrect statements. Options A, C, and D either include correct statements or miss incorrect ones. This question tests the ability to differentiate accurate descriptions of Porifera from common misconceptions or characteristics of other phyla, focusing on body plan, digestion, and skeletal support.