Final answer:
The statement that a pseudocoelom has mesodermal lining on one side and endodermal on the other while a true coelom is completely lined by mesoderm is true. Pseudocoelomates, like roundworms, have a "false" coelom, whereas eucoelomates, such as earthworms and vertebrates, have a completely mesoderm-lined true coelom.
Step-by-step explanation:
True or false: A pseudocoelom is lined on one side by mesoderm and on the other side by endodermally derived tissue (gastrodermis). A true coelom is lined on both sides by mesoderm. The statement is true.A pseudocoelom is indeed partially lined by mesoderm and partially by endodermal tissue, which is why it is considered a "false" coelom. Organisms with this type of body cavity, such as the Nematoda (roundworms), are referred to as pseudocoelomates.
On the contrary, a true coelom, found in eucoelomates like earthworms, snails, insects, starfish, and vertebrates, is entirely enclosed within the mesoderm. This coelom formation can differ in protostomes and deuterostomes based on embryonic development. Protostomes typically exhibit schizocoely, where the mesoderm splits to form a coelom, whereas deuterostomes follow enterocoely, with the mesoderm forming as buds off of the gut. These examples illustrate the evolutionary impact of coelom formation on various animal species.