question_answer 50)

  Real organs are absent in (a) Mollusca       (b) Coelenterata              (c) Arthropoda                  (d) Echinodermata

Answer:

  (b) Coelentrates are multicellular, diploblastic and acoelomate animals having tissue level of organization i.e., they lack true organs, mollusca, Arthropoda and Echinodermata have organ level of organization.