Question 1

Which of the following protozoa is most commonly associated with causing dysentery by infecting the large intestine?

Accepted Answer

Entamoeba histolytica

Question 2

A patient presents with recurring fever and chills after returning from a trip to Africa. Blood smears reveal ring-shaped parasites inside red blood cells. Which protozoan is most likely responsible, and what is its primary infection site?

Accepted Answer

Plasmodium species; red blood cells

Question 3

Which of the following best distinguishes Platyhelminthes from Nematoda?

Accepted Answer

Platyhelminthes are dorsoventrally flattened, while Nematoda are cylindrical and unsegmented.

Question 4

Which of the following is a correct example of a monoecious organism?

Accepted Answer

Taenia solium

Question 5

A parasite requires two different hosts to complete its life cycle. In one host, it undergoes sexual reproduction, and in the other, it undergoes asexual reproduction. What are the correct terms for these hosts?

Accepted Answer

Definitive host (sexual), Intermediate host (asexual)

Question 6

Which of the following best describes a reservoir host?

Accepted Answer

A host that harbors the parasite and serves as a source of infection for others

Question 7

Which of the following helminths is correctly matched with its category?

Accepted Answer

Schistosoma haematobium – Trematode

Question 8

A patient is diagnosed with a tapeworm infection after eating undercooked pork. Which of the following statements is correct regarding the organism involved?

Accepted Answer

It is a cestode and is monoecious.

Question 9

Which of the following equations correctly represents the relationship between the number of hosts ($$n$$), the number of parasite generations ($$g$$), and the number of completed life cycles ($$c) if $$each host supports one generation per cycle?

Accepted Answer

$$c = \frac{g}{n}$$

Question 10

A child presents with perianal itching, and microscopic examination reveals oval eggs with a flattened side. Which helminth is most likely responsible, and to which group does it belong?

Accepted Answer

Enterobius vermicularis; Nematode

Question 11

Which of the following statements about dioecious organisms is correct?

Accepted Answer

They require two individuals for sexual reproduction.

Question 12

A patient is found to have Schistosoma mansoni eggs in their stool. Which of the following is true regarding the life cycle of this parasite?

Accepted Answer

Snails serve as the intermediate host.

Question 13

Which of the following is an example of an accidental host?

Accepted Answer

A human infected with Echinococcus granulosus after contact with dog feces

Question 14

Which of the following best describes the difference between a cestode and a trematode?

Accepted Answer

Cestodes are segmented, while trematodes are unsegmented and leaf-shaped.

Question 15

Which of the following protozoa infects the urogenital tract and is transmitted primarily through sexual contact?

Accepted Answer

Trichomonas vaginalis

Question 16

A nematode infection is suspected in a patient with eosinophilia and a history of eating undercooked pork. Which nematode is most likely responsible?

Accepted Answer

Trichinella spiralis

Question 17

Which of the following statements about intermediate hosts is correct?

Accepted Answer

They are required for the parasite's asexual reproduction or development.

Question 18

Which of the following is a dioecious nematode that infects humans?

Accepted Answer

Ascaris lumbricoides

Question 19

A patient is diagnosed with giardiasis. Which of the following best describes the infection site and transmission route of Giardia lamblia?

Accepted Answer

Small intestine; fecal-oral route

Question 20

Which of the following equations correctly represents the probability $$P of a $$human acquiring a nematode infection after exposure to $$n$$ infective larvae, given that the probability of infection from a single larva is $$p$$?

Accepted Answer

$$P = 1 - (1 - p)^n$$

Helminths and Protozoa: Classification, Hosts, and Infection Sites

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