Question

Which one of the following does not have an intermediate host?
A. Tapeworm
B. Ascaris
C. Liver fluke
D. Plasmodium

Answer 1

Hint: A host is an organism that harbours a parasitic, mutualistic, or a commensalistic guest . The guest is mainly provided with nourishment and shelter. For Examples animals playing host to parasitic worms (e.g. nematodes), cells harbouring pathogenic (disease-causing) viruses, a bean plant hosting mutualistic (helpful) nitrogen-fixing bacteria.The host range is the collection of hosts that an organism can use as a partner.

Complete answer:
Types of hosts
Definitive or primary host - an organism in which the parasite reaches the adult stage and reproduces sexually, if it is possible. And it is the final host.
Secondary or intermediate host - an organism that harbors the sexually immature parasite and is required by the parasite to undergo development and complete its life cycle. It usually acts as a vector of the parasite to reach its definitive host.
Tapeworms are known to be a highly diversified group of endoparasites; they generally have a two-phase life cycle: vertebrates serve as final hosts and all orders may utilize arthropods, other invertebrates or even vertebrates as first intermediate hosts . Ascaris lumbricoides is the largest and, globally, the most widespread of all human intestinal roundworms (Nematode). In their Life cycle: Human is the definitive host. There is no intermediate host.
Liver fluke can infect all the grazing animals and man but it mainly affects sheep and cattle. It is most pathogenic in sheep. Compared to other helminths, their lifecycle is complex and involves an intermediate host, the mud snail Galba (Lymnaea) truncatula and several free-living stages.
There are approximately 156 named species of Plasmodium which infect various species of vertebrates. Four of the species are considered true parasites of humans, as they utilize humans almost exclusively as a natural intermediate host.

Hence the correct answer is OPTION(B)

Note: An intermediate host acts as a vector of parasites to reach its definitive host (where it will become mature). so, the intermediate host serves only as a site wherein the parasite spends a particular developmental stage of its life cycle that is the larval stage.