Question

Which one is a monogenetic parasite?
a. Plasmodium
b. Fasciola hepatica
c. Taenia solium
d. Entamoeba histolytica

Answer 1

A close association between two organisms of different species where one is benefited and the other one is often adversely affected is called parasitism. The organism that takes nourishment is called parasite, and the organism from which the nourishment is taken is called the host.

Complete answer:
Monogenetic parasites are the parasites that complete their life cycles in one host only. Digenetic parasites are those that need more than one host (usually two) to complete their life cycles.

Among the given options:

Plasmodium, the malaria parasite is a protozoan parasite and its life cycle is digenetic, as it requires two hosts to complete its life cycle - an invertebrate female anopheles mosquito as its primary host (where sexual reproduction occurs) and a vertebrate (man) as its secondary or intermediate host (where asexual reproduction happens).

Fasciola hepatica (liver fluke) is an endoparasite, which completes its life history in two hosts. The adult Fasciola is found in the liver and bile duct of sheep and goat which are its primary hosts. The secondary or intermediate host is a pond snail (a mollusc). Thus, it is also digenetic.

Taenia solium is a tapeworm that causes taeniasis. It is mostly found in those countries, where pork is taken as food. The adults of T. solium are parasites in the small intestine of human beings (primary host) and its larva is mostly found in the muscles of the pig (secondary host). Thus, it is also digenetic.

Entamoeba histolytica is a protozoan parasite that is responsible for a disease known as amoebiasis. It occurs usually in the large intestine of humans. Its life cycle is monogenetic because it does not require any intermediate host.

Note: Parasites are known as the organisms that live on or in host organisms and get their food from or at the expense of their host. Majorly, there are three classes of parasites that can cause various diseases in humans: helminths, protozoa, and ectoparasites.