Concept explainers
Introduction: All sponges belong to a phylum called Porifera. They are the simplest animals with cellular level of organization. They have diverged from other animals early in the evolution. They have a very simple body structure composed of only two layers of cells. In between the two layers, a gelatinous region is present called mesohyl. The exchange of nutrient and waste material takes place through diffusion in sponges.
Answer to Problem 1TYU
Correct answer: Collar cells (chaonocytes) are characteristics of poriferans. Hence, the correct answer is option (a).
Explanation of Solution
Reason for the correct answer:
Option (a) is given as “poriferans”. The interior space of the body of poriferans is characterized by numerous canals lined with flagellate choanocytes. These cells help to capture food particles. They generate water flow through the body of the sponges. Hence, the correct answer is option (a).
Reasons for the incorrect answers:
Option (b) is given as “cnidarians”. Cnidarians are characterized by cnidocytes. Hence, option (b) is incorrect.
Option (c) is given as “most celomates”. Collar cells are characteristics of acelomate that is in poriferans. Hence, option (c) is incorrect.
Option (d) is given as, “lophotrochozoans”. Collar cells (chaonocytes) are not the characteristics of lophotrochozoans. Hence, option (d) is incorrect.
Option (e) is given as “ecdysozoans”. Ecdysozoans lack collar cells. Hence, option (e) is incorrect.
Hence, options (b), (c), (d), and (e) are incorrect.
Cnidarians are characterized by the presence of collar cells.
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Chapter 31 Solutions
Biology (MindTap Course List)
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