NEW
Font size
WorksheetsIntroduction to Parasitology and Hosts
Total questions: 14
Worksheet time: 7mins
A research team is modeling parasite–host dynamics in humans. Based on the provided definitions: Which statement best explains why parasites typically do not kill their hosts?
Parasites are free-living organisms that obtain energy independently of hosts, so host survival is irrelevant.
Parasites rely on hosts for survival, growth, and reproduction, so killing the host would remove their essential resource.
Parasites are always visible to the human eye and can be removed before they cause serious harm.
Parasites primarily infect non-human organisms, making lethal outcomes in humans rare.
You are tasked with designing a control strategy for malaria transmission using the classifications provided. Which intervention target is most directly aimed at disrupting the transmission of an endoparasite via its carrier?
Reducing lice and fleas on domestic animals to control ectoparasites
Eliminating reservoir hosts to prevent parasite size variation
Targeting the mosquito to interrupt its role as a vector that transmits Plasmodium to humans
Increasing visibility of parasites to the human eye to improve detection
A clinician needs to obtain a high-quality sputum sample to detect respiratory parasites. Which collection instruction best aligns with the guidance provided:
Ask the patient to cough gently and collect saliva from the mouth into a container
Instruct the patient to cough up sputum from as far down in the lungs as possible
Request the patient to breathe normally and provide exhaled air in a bag
Collect sputum using only a dry swab from the lips
A laboratory plans a survey of parasitic diseases and must organize teams by subdiscipline. Based on the classification framework, which pairing correctly matches the subdiscipline with its scope:
Medical Protozoology — study of arthropods that transmit disease to humans
Medical Helminthology — study of medically important protozoa
Medical Entomology — study of arthropods that cause or transmit disease to humans
Medical Entomology — study of worms (helminths) affecting humans
A researcher is classifying parasites following zoological nomenclature. Which sequence correctly orders taxonomic ranks as specified:
Genus, Species, Phylum, Class, Order, Family, Subphylum
Phylum, Subphylum, Class, Order, Family, Genus, Species
Species, Genus, Family, Order, Class, Subphylum, Phylum
Order, Class, Subphylum, Phylum, Family, Genus, Species
During stool examination for amoebae, which genus-species pairing reflects the Sarcodina (Amoebae) classification given:
Schistosoma mansoni under Platyhelminthes: Trematodea
Entamoeba histolytica under Sarcodina (Amoebae)
Fasciola hepatica under Sarcodina (Amoebae)
Endolimax nana under Platyhelminthes: Trematodea
Using the classification details provided, which pairing correctly matches a parasite group with an example or genus explicitly listed: Mastigophora (Flagellates), Cestoda—Genus Taenia, Cestoda—Genus Echinococcus, or Genus Dientameba? Choose the option that best aligns with the text-based taxonomy shown.
Mastigophora (Flagellates) paired with Taenia saginata
Cestoda paired with Genus Taenia (e.g., T. saginata)
Cestoda paired with Genus Dientameba (e.g., Dientameba fragilis)
Genus Echinococcus classified under Mastigophora
You are screening a fresh stool specimen for intestinal protozoa. To preserve motility while enhancing visualization, which wet mount choice and rationale best align with the procedure described:
Iodine wet mount, because iodine preserves trophozoite motility and highlights nuclei
Saline wet mount, because saline maintains live motile trophozoites without killing them
Oil immersion saline mount, because oil immersion clarifies morphology without affecting movement
Methylene blue alone, because the dye stains glycogen vacuoles and maintains motility
A lab must choose a concentration method to maximize recovery of roundworm eggs and protozoan cysts during mass screening. Which option is the most appropriate based on the described techniques, and why?
Zinc sulfate flotation, because it is simple, efficient, and recommended for mass examination of roundworm eggs and protozoan cysts
Formalin–ethyl acetate sedimentation, because flotation damages cysts and only recovers operculate eggs
Iodine-saline direct smear, because concentration is unnecessary when parasites are scarce
Glycerol wet mount, because glycerol’s hygroscopic nature selectively floats helminth eggs
A clinician examines fresh dysenteric stool and observes trophozoites with rapid, progressive, unidirectional motility via pseudopodia and ingested RBCs in the cytoplasm. Based on reasoning from morphological and laboratory features, which organism and infection stage most strongly explain these findings?
Entamoeba coli trophozoite, non-pathogenic infection
Entamoeba histolytica trophozoite, pathogenic amoebiasis
Entamoeba gingivalis trophozoite, oral commensal
Entamoeba histolytica mature cyst, intestinal infection stage
Public health workers investigate two clusters: Cluster A involves diarrheal disease traced to ingestion of water contaminated with quadrinucleate cysts; Cluster B involves oral colonization transmitted by direct person-to-person contact (kissing) with no cyst formation. Which correct pairing identifies the organisms responsible for Cluster A and Cluster B, respectively?
Cluster A: Entamoeba gingivalis; Cluster B: Entamoeba coli
Cluster A: Entamoeba coli; Cluster B: Entamoeba histolytica
Cluster A: Entamoeba histolytica; Cluster B: Entamoeba gingivalis
Cluster A: Entamoeba gingivalis; Cluster B: Entamoeba histolytica
A patient presents with intermittent abdominal discomfort. Stool concentration methods are negative, but permanently stained fecal smears (trichrome) reveal an irregular, roundish protozoan measuring about 8–10 µm, with progressive motility via hyaline broad pseudopodia and cytoplasm containing two nuclei each with 4–8 central chromatin granules and no peripheral chromatin. Which targeted diagnostic plan best aligns with this organism’s biology and the evidence provided?
Repeat stool concentration and antigen assays to detect the cyst stage of Dientamoeba fragilis, which is the diagnostic form in feces
Order serial trichrome-stained stool smears to detect trophozoites of Dientamoeba fragilis, acknowledging that cysts have not been identified and concentration methods are unreliable
Switch to wet-mount microscopy to visualize motile cysts of Endolimax nana, which are typically diagnostic in fresh stool
Perform serologic testing for invasive amoebiasis, since the organism’s trophozoite is pathogenic and disseminates hematogenously
A public health team investigates a cluster of prolonged watery diarrhea in hikers who drank from untreated streams. Stool antigen testing by ELISA is positive, and wet mounts from semi-formed stools show both cysts and trophozoites with bilateral symmetry, two nuclei with large central karyosomes, four pairs of flagella, two axonemes, and a ventral suction disc. Based on this evidence, which organism is the most likely cause?
Giardia lamblia
Chilomastix mesnili
An intestinal hemoflagellate
A genital flagellate
A lab receives three stool specimens from one patient on different days. The first is freshly liquid, the second is formed, and the third is semi-formed. Using only wet preparation, which finding pattern best aligns with recommended laboratory diagnosis for flagellates discussed: liquid shows only trophozoites; formed shows only cysts; semi-formed may show both stages?
Liquid: trophozoites only; Formed: cysts only; Semi-formed: both trophozoites and cysts
Liquid: cysts only; Formed: trophozoites only; Semi-formed: neither stage
Liquid: both stages; Formed: trophozoites only; Semi-formed: cysts only
Liquid: neither stage; Formed: both stages; Semi-formed: trophozoites only
