A parasitic organism is identified with the following features: an unsegmented, elongated, cylindrical body; a pseudocoelom; a complete digestive tract; and a thick, resistant cuticle. Which of the following diseases is most likely caused by an organism with these characteristics?
Correct: B
The features described—unsegmented, elongated, cylindrical body, pseudocoelom, complete digestive tract, and thick cuticle—are classic characteristics of Phylum Aschelminthes (Nematoda or roundworms).
- Malaria is caused by Plasmodium, a protozoan (Kingdom Protista).
- Ascariasis is caused by Ascaris lumbricoides, a roundworm belonging to Phylum Aschelminthes. This matches the description.
- Schistosomiasis is caused by Schistosoma (blood flukes), which are Platyhelminthes (flatworms), characterized by an incomplete digestive system, acoelomate body, and lack of segmentation.
- Taeniasis is caused by Taenia solium (pork tapeworm), which are also Platyhelminthes (cestodes), characterized by an incomplete digestive system (or absent, relying on absorption), acoelomate body, and segmentation (proglottids).
Therefore, Ascariasis is the disease caused by an organism matching the given description.