Question

The layer absent in the embryos of diploblastic animals is
A) Ectoderm
B) Mesoderm
C) Endoderm
D) Mesoglea

Answer 1

Hint:Diploblastic animals have such a blastula that includes ctenophora and Cnidaria. The jellyfish, comb jellies, and sea anemones are diploblastic in nature.

Complete answer:
To answer this question, we should first understand the meaning of diploblastic. The organisms that have ctenophora and Cnidaria are the diploblastic animals. They are called diploblastic because of the presence of two germ layers; endoderm and ectoderm. The diploblastic animals do not develop true organs due to the absence of mesoderm On the other hand the triploblastic structure developed in higher and intermediate animals. They have three germ layer ectoderm, endoderm, and mesoderm; the mesoderm is developed in between the other two layers because of the presence of this third layer triploblastic animals can develop true organs. The triploblastic animals include all the multicellular animals except some of the invertebrates like sponges and cnidarians even humans are triploblastic in nature. The diploblastic animals include the jellyfish, sea anemones, etc that match this characteristic. The animals of phylum coelenterata or cnidaria and poriferans are some of the animals that are diploblastic in nature.
Now, mesoderm is a germ layer that is only found in triploblastic organisms. This germ layer gives rise to the bones, connective tissue, skeleton muscles, heart, and the urogenital system. This germ layer is not found in diploblastic organisms therefore, they are unicellular in nature.

Hence, the correct answer is ‘B’. Mesoderm.

Note:Endoderm is a cell that forms some organs like colon, intestine, stomach, liver, lungs, and the pancreas. While ectoderm produces the outer lining of the body that includes hair and epidermis and both these germ layers are found in diploblastic organisms.