Protozoa: Characteristics, Life Cycle, and Motility

30 Questions

What is the characteristic of protozoa that allows them to perform whole life functions?

They are eukaryotic

What is the mode of reproduction in which the nucleus undergoes multiple divisions before the cell divides?

Schizogony

What is the term for the process of production and fusion of gametes in protozoa?

Gametogony

Which of the following is NOT a type of motility found in protozoa?

Cytokinesis

Which classification of protozoa includes Entamoeba histolytica?

Amebae

What is the stage of Entamoeba histolytica that has an ameboid appearance due to the presence of pseudopodia?

Trophozoite

How is Entamoeba histolytica typically transmitted to humans?

Through contaminated food or water

What is the disease caused by Entamoeba histolytica in the liver?

Liver abscess

Which of the following is an example of a Ciliate protozoa?

Balantidium coli

What is the term for the fusion of genetic material between different mating types in Ciliophora?

Conjugation

What is the characteristic of the trophozoite of Entamoeba histolytica?

One ingested red blood cell and one nucleus

What is the treatment for intestinal amebiasis?

Metronidazole or tinidazole

What is the characteristic of the cyst of Giardia lamblia?

The cytoplasm contains four nuclei

What is the treatment for trichomoniasis?

Metronidazole

What is the disease caused by Plasmodium falciparum?

Malaria

What is the vector for Trypanosoma cruzi?

Reduviid bug

What is the characteristic of the life cycle of Leishmania?

Vector: sandfly, infective stage: metacyclic promastigotes

What is the characteristic of the Trematodes?

Flattened, leaf-like, and bilaterally symmetrical

What is the characteristic of Schistosoma haematobium?

Separate sexes, eggs with spine, and cercaria is the infective stage

What is the characteristic of the digestive system of Nematodes?

Present

Which parasite is responsible for urinary schistosomiasis?

Haematobium

What is the mode of infection for Taenia saginata?

Ingestion of raw or improperly cooked beef

What is the most common symptom of pinworm infection?

Perianal pruritus

Which of the following parasites causes ascariasis?

Ascaris lumbricoides

What is the infective stage of Wuchereria bancrofti?

Infective larvae

What is the name of the disease caused by Wuchereria bancrofti?

Elephantiasis

What is the mode of infection for Hymenolepis nana?

Ingestion of eggs through contaminated food

What is the clinical finding in heavy infections of Ascaris lumbricoides?

Malnutrition and intestinal obstruction

What is the definitive host for Taenia saginata?

Human

What is the infective stage of Enterobius vermicularis?

Egg

Study Notes

Helminths

Haematobium: found in venous plexus of bladder, ureter, and kidneys; causes urinary schistosomiasis; eggs pass in urine
Taenia saginata (beef tapeworm): causes taeniasis saginata
- Morphology: scolex, segmented with 1000-2000 segments
- Life cycle: human as definitive host, cattle as intermediate host; infective stage: cysticercus bovis; mode of infection: ingestion of raw or improperly cooked beef
Hymenolepis nana (Dwarf tapeworm): causes hymenolepiasis nana
- Life cycle: adult worms in small intestine; definitive hosts: human, rats, and mice; infective stage: egg; mode of infection: ingestion of eggs through contaminated food or autoinfection
Enterobius vermicularis (pinworm): causes pinworm infection (enterobiasis)
- Life cycle: infective stage: egg; mode of infection: ingesting worm eggs; clinical findings: perianal pruritus
Ascaris lumbricoides: causes ascariasis
- Life cycle: infective stage: egg; mode of infection: ingesting eggs in food or water contaminated with human feces; clinical findings: most infections are asymptomatic, malnutrition and intestinal obstruction in heavy worm burden patients
Wuchereria: causes elephantiasis
- Life cycle: infective stage: infective larvae; mode of infection: humans infected through female mosquito bite; clinical findings: adult worms in lymph nodes cause inflammation that eventually obstructs lymphatic vessels, causing edema (elephantiasis)

Protozoa

General characteristics: unicellular, eukaryotic, complex life cycle, motility through flagella, cilia, or amoeboid movement
Reproduction: asexual (binary fission, schizogony) and sexual (gametogony, conjugation)
Intestinal protozoa: significant to human health, including:
- Entamoeba histolytica: causes amebic dysentery and liver abscess
  - Morphology: trophozoite with ameboid appearance, cyst with 1-4 nuclei
  - Life cycle: no intermediate or reservoir hosts; infective stage: mature cysts; mode of infection: feco-orally through contaminated food or hands
- Giardia lamblia: causes giardiasis
  - Morphology: trophozoite with 8 flagella and 2 axostyles; cyst with 4 nuclei
- Trichomonas vaginalis: causes trichomoniasis
  - Morphology: trophozoite with 4-6 flagella; no cyst stage
  - Life cycle: infective stage: trophozoites; mode of infection: primarily through sexual contact
Blood and tissue protozoa: including Plasmodium, Trypanosoma, and Leishmania
- Plasmodium: causes malaria
  - Four species infect humans: P. vivax, P. ovale, P. malariae, and P. falciparum
- Trypanosoma: includes T. cruzi (Chagas' disease), T. gambiense, and T. rhodesiense (African trypanosomiasis)
- Leishmania: causes leishmaniasis
  - L. donovani causes visceral leishmaniasis (kala-azar)

Learn about the general characteristics of protozoa, including their eukaryotic nature, complex life cycle, and different types of motility. Discover how these single-celled organisms reproduce and move through their environment.

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