EVERYDAY SCIENCE

Detailed explanation-1: -A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host. There are three main classes of parasites that can cause disease in humans: protozoa, helminths, and ectoparasites. Protozoa. Entamoeba histolytica is a protozoan.

Detailed explanation-2: -(PAYR-uh-SITE) An animal or plant that gets nutrients by living on or in an organism of another species. A complete parasite gets all of its nutrients from the host organism, but a semi-parasite gets only some of its nutrients from the host.

Detailed explanation-3: -Parasites are usually smaller than their host. Parasites use both invertebrate and vertebrate hosts. Adult parasites may live on the host (e.g. lice), in the host (e.g. tapeworms) or feed on a host occasionally (e.g. mosquitoes).

Detailed explanation-4: -Protozoa: Protozoa are single-celled organisms that can multiply in humans. Helminths: Helminths are parasitic worms that often root in a person’s digestive tract. Ectoparasites: Ectoparasites are small organisms that live on the outside of the body.