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Multiple Choice
One of the primary developmental/anatomical characteristics distinguishing the major animal phyla is the condition of the body cavity. A pseudocoelomate animal is one in which the body cavity is __________.
A
bounded completely by mesoderm
B
filled by a solid mass of mesoderm
C
bounded completely by endoderm
D
bounded partly by ectoderm
E
lined on one side by mesoderm and on the other side by endoderm
Verified step by step guidance
1
Understand the concept of a body cavity in animals, which is a fluid-filled space between the digestive tract and the body wall.
Recognize the different types of body cavities: acoelomate (no body cavity), pseudocoelomate (body cavity not completely lined by mesoderm), and coelomate (body cavity completely lined by mesoderm).
Identify that a pseudocoelomate animal has a body cavity called a pseudocoel, which is not completely lined by mesoderm.
Note that in pseudocoelomates, the body cavity is lined on one side by mesoderm and on the other side by endoderm.
Conclude that the correct description of a pseudocoelomate's body cavity is that it is lined on one side by mesoderm and on the other side by endoderm.