Animal tissues develop from embryonic germ layers. Triploblastic animals have three germ layers (ectoderm, mesoderm, and endoderm) and three basic body plans related to body cavities (acoelomate, pseudocoelomate, and coelomate).

Select the three statements that are true. To review the germ layers and the terminology associated with body cavities, see the Hints.

A diploblast has no mesoderm.

A pseudocoelom has the same functions as a true coelom.

In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the tissue lining the outer side of the body cavity.

The digestive tract of a coelomate functions as a coelom.

An acoelomate triploblast has no endoderm.

In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the lining of the digestive tract.

In a pseudocoelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the muscles.

True statements are

A diploblast has no mesoderm.

A pseudocoelom has the same functions as a true coelom.

In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the tissue lining the outer side of the body cavity.

Explanation:

Diploblastic animals (radially symmetric animals like jelly fish, sea anemone) has only two layers – the endoderm and the ectoderm. It does not have mesoderm germ layer. Diploblastic animals are formed from the embryonic process called gastrulation from a blastula cells.

A true coelom and pseudocoelom may differ in their structure or location but their main function is the same. Since both are fluid-filled cavities, they act as hydrostatic skeleton disseminating extra pressure via the body to protect the internal organs and minimize damage.

Each germ layer gives rise to tissues pertaining to a particular organ or organ system. Like the mesoderm provides for muscles, nervous system and the endoderm gives rise to gastrointestinal organs, lungs etc. So the tissues lining outside and inside the body cavity will arise from the same germ layer.