The body cavity of Ascaris is a pseudocoel because
A. It contains cells termed pseudocoelocytes
B. It is bound internally by intestines
C. It has very little parenchyma
D. It has no mesoderm surrounding the gut
D. It has no mesoderm surrounding the gut
D. It has no mesoderm surrounding the gut
To determine the correct answer, let's break down the options and analyze each one:
A. It contains cells termed pseudocoelocytes: This statement does not provide an accurate reason for why the body cavity of Ascaris is a pseudocoel. Pseudocoelocytes are cells found in certain organisms, but their presence alone does not define the nature of the body cavity.
B. It is bound internally by intestines: While this statement describes a characteristic of the body cavity, it does not explain why it is a pseudocoel. Intestines are present in the cavity, but this alone does not define its nature.
C. It has very little parenchyma: Parenchyma refers to the functional tissue within an organ, but it is not directly related to the classification of the body cavity. This option does not provide a valid reason for why the body cavity is a pseudocoel.
D. It has no mesoderm surrounding the gut: This option correctly explains why the body cavity of Ascaris is a pseudocoel. The absence of mesoderm surrounding the gut indicates that the body cavity is not fully lined with a mesodermal layer, which is a characteristic of a true coelom. A pseudocoel is a body cavity that is only partially lined by mesoderm, and this is the defining characteristic for Ascaris.
Therefore, the correct answer is D. It has no mesoderm surrounding the gut.