How could a biologist distinguish an acoel flatworm from a free living platyhelminth?Group of answer choicesThe acoel worm would be solid throughout, since it lacks a gut.The acoel worm would have a nervous system.Only the acoel is triploblastic.The platyhelminth would have a more primitive gut and nervous system.

A biologist could distinguish an acoel flatworm from a free-living platyhelminth based on their anatomical and physiological differences.

1. Gut Structure: The acoel flatworm is acoelomate, meaning it lacks a body cavity and a gut. Its body is solid throughout. On the other hand, platyhelminths have a primitive gut, often a gastrovascular cavity, which serves both digestive and circulatory functions.

2. Nervous System: Both acoel flatworms and platyhelminths have a nervous system. However, the nervous system of platyhelminths is often more primitive compared to that of acoel flatworms.

3. Germ Layers: Acoel flatworms are triploblastic, meaning they develop from three germ layers: the ectoderm, mesoderm, and endoderm. Platyhelminths are also triploblastic. Therefore, this characteristic cannot be used to distinguish between the two.

In conclusion, the key distinguishing features would be the presence of a gut in platyhelminths and the absence of one in acoel flatworms, and the complexity of their nervous systems.

A biologist could distinguish an acoel flatworm from a free-living platyhelminth through the following steps:

1. Examine the Internal Structure: The acoel worm would be solid throughout, since it lacks a gut. This is a key distinguishing feature as platyhelminths have a gut.

2. Check for the Presence of a Nervous System: Both acoel worms and platyhelminths have a nervous system. However, the complexity of the system may vary.

3. Determine the Level of Tissue Organization: Both acoel and platyhelminths are triploblastic, meaning they have three primary germ layers: the ectoderm, mesoderm, and endoderm. This is not a distinguishing feature.

4. Compare the Complexity of the Gut and Nervous System: The platyhelminth would have a more primitive gut and nervous system compared to the acoel worm. This could be determined through detailed microscopic examination.

By following these steps, a biologist could distinguish between an acoel flatworm and a free-living platyhelminth.