Final answer:
Parasitism is a type of symbiotic relationship in which one species benefits while the other is harmed. It involves a parasite that is dependent on and lives at the expense of a host. Roundworms are an example of parasites that harm their mammalian hosts.
Step-by-step explanation:
Parasitism is a type of association between two organisms in which one of them, the parasite, is dependent on and lives at the expense of the other, the host. The host provides the parasite with a habitat and with nourishment. Internal parasites live within the host's body, as in the case of the parasitic worms that are found in the intestines of animals, and various bacteria that live and multiply in internal organs. External parasites, like the fleas of mammals and the mistletoes of plants, live on the outside surface of the host, but still derive nourishment from it.
Parasitism is a symbiotic relationship in which one species benefits (the parasite) while the other species is harmed (the host).
For example, roundworms are parasites of mammals, including humans, cats, and dogs. They live in the intestines and absorb the nutrients from their host's food, causing harm to the host.