Identify the labelled parts A to D in sections of (i) diploblastic and (ii) triploblastic organisations in animals. A B C D (a) Mesoglea Ectoderm Endoderm Mesoderm (b) Endoderm Mesoderm Mesoglea Ectoderm (c) Mesoderm Mesoglea Ectoderm Endoderm (d) Ectoderm Endoderm Mesoglea Mesoderm

Step-by-step solution

Animals in which the cells are arranged in two embryonic layers, an external ectoderm and an internal endoderm, are called diploblastic. An undifferentiated layer, mesoglea, is present in between the ectoderm and the endoderm. Those animals in which the developing embryo has a third germinal layer, mesoderm, in between the ectoderm and endoderm, are called triploblastic animals (platyhelminthes to chordates).