Which of the following organisms is not an endoparasite?

The organism that is not an endoparasite is the tick. Endoparasites are parasites that live inside the host's body, while ectoparasites live on the outside of the host's body. Roundworms, liver flukes, and cestodes (also known as tapeworms) are all endoparasites, as they live inside the body of the host they are feeding on. However, ticks are ectoparasites, which means they live on the outside of the host's body and feed on their blood. While ticks can transmit diseases to their host, they do not live inside the host's body like endoparasites do. In summary, ticks are ectoparasites and are not considered endoparasites, unlike roundworms, liver flukes, and cestodes.