Protozoa Practice Questions
20 free Protozoa practice questions for the General Science. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
Which of the following structures is primarily used by Amoeba proteus for locomotion and capturing food?
- A Cilia
- B Flagella
- C Pseudopodia
- D Undulating membrane
Correct answer: Pseudopodia
Amoeba move and feed using pseudopodia, which are temporary cytoplasmic extensions. This process is known as amoeboid movement and involves the transition between endoplasm and ectoplasm.
The definitive host of Plasmodium falciparum, where the sexual stage of the life cycle occurs, is the:
- A Human liver cell
- B Human red blood cell
- C Female Anopheles mosquito
- D Male Culex quinquefasciatus mosquito
Correct answer: Female Anopheles mosquito
The sexual phase (sporogony) of the malaria parasite occurs within the gut of the female Anopheles mosquito. Humans serve as the intermediate host where asexual reproduction takes place.
Which organelle is responsible for osmoregulation in freshwater protozoa by expelling excess water?
- A Contractile vacuole
- B Food vacuole
- C Endoplasmic reticulum
- D Cytostome
Correct answer: Contractile vacuole
Freshwater protozoa are hypertonic to their environment, causing water to constantly enter the cell. The contractile vacuole collects and periodically pumps out this excess water to prevent the cell from bursting.
Giardia lamblia, a flagellated protozoan that causes diarrheal illness, typically colonizes which part of the human body?
- A Large intestine
- B Small intestine
- C Stomach
- D Esophagus
Correct answer: Small intestine
Giardia trophozoites attach to the mucosal surface of the small intestine using a ventral sucking disc. This attachment interferes with nutrient absorption, leading to malabsorption and diarrhea.
Which protozoan is known for its ability to change its cell shape due to the presence of a flexible pellicle and possesses a 'red eye spot'?
- A Amoeba
- B Plasmodium
- C Trypanosoma
- D Euglena
Correct answer: Euglena
Euglena is a mixotrophic protozoan that contains chloroplasts and a photoreceptive eyespot (stigma). Its flexible pellicle allows for 'euglenoid movement' or metaboly.
African Sleeping Sickness is caused by a protozoan transmitted through the bite of which vector?
- A Sandfly
- B Reduviid bug
- C Deer tick
- D Tsetse fly
Correct answer: Tsetse fly
The disease is caused by Trypanosoma brucei, which is transmitted to humans by the Tsetse fly (Glossina genus). The parasite eventually crosses the blood-brain barrier, leading to neurological symptoms.
Which process in Paramecium involves the exchange of genetic material between two individuals?
- A Binary fission
- B Budding
- C Conjugation
- D Schizogony
Correct answer: Conjugation
Conjugation in Paramecium is a sexual process in which two organisms pair and exchange micronuclear material. It increases genetic diversity but does not by itself increase the number of individuals.
The 'Infective Stage' of Entamoeba histolytica for humans is the:
- A Uninucleate trophozoite
- B Immature uninucleate precyst
- C Merozoite
- D Mature quadrinucleate cyst
Correct answer: Mature quadrinucleate cyst
The mature cyst is resistant to environmental stress and gastric acid, allowing it to pass through the stomach safely. Once in the intestine, it excysts to release motile trophozoites.
Which group of protozoa is strictly parasitic and lacks specialized locomotor organelles in their adult stage?
- A Sarcodina
- B Mastigophora
- C Ciliophora
- D Apicomplexa
Correct answer: Apicomplexa
Apicomplexans, such as Plasmodium, are characterized by an apical complex used for host cell entry. They lack cilia or flagella for locomotion in most stages of their life cycle.
Chagas disease, caused by Trypanosoma cruzi, is primarily transmitted by:
- A Fecal contamination from Triatomine bugs
- B Saliva injected during a mosquito blood meal
- C Contaminated drinking water
- D Consumption of undercooked pork
Correct answer: Fecal contamination from Triatomine bugs
Triatomine bugs, or 'kissing bugs,' defecate while feeding; the parasite is found in the feces and enters the host through the bite wound or mucous membranes. This is known as stercorarian transmission.
Which of the following protozoans causes a common sexually transmitted infection (STI)?
- A Trichomonas vaginalis
- B Cryptosporidium parvum
- C Leishmania donovani
- D Toxoplasma gondii
Correct answer: Trichomonas vaginalis
Trichomonas vaginalis is a flagellated protozoan that exists only in the trophozoite stage. It causes trichomoniasis, which affects the urogenital tract of both men and women.
The process of multiple fission, where a single mother cell divides into many daughter cells simultaneously, is called:
- A Syngamy
- B Plasmotomy
- C Schizogony
- D Cytokinesis
Correct answer: Schizogony
Schizogony is an asexual reproductive process common in Apicomplexans. The nucleus undergoes multiple divisions before the cytoplasm divides, resulting in many merozoites.
Which protozoan is associated with causing 'Primary Amoebic Meningoencephalitis' (PAM) after swimming in warm freshwater?
- A Acanthamoeba
- B Entamoeba coli
- C Balamuthia mandrillaris
- D Naegleria fowleri
Correct answer: Naegleria fowleri
Naegleria fowleri is often called the 'brain-eating amoeba.' It enters the body through the nose, travels along the olfactory nerve, and destroys brain tissue.
Which structure in Ciliates like Paramecium is used specifically for the intake of food?
- A Contractile vacuole
- B Cytoproct
- C Cytostome
- D Macronucleus
Correct answer: Cytostome
The cytostome acts as a 'cell mouth' where food particles are directed by cilia. The food then passes into the cytopharynx to form a food vacuole.
Leishmaniasis is transmitted to humans by the bite of infected female:
- A Anopheles mosquitoes
- B Black flies
- C Fleas
- D Sandflies
Correct answer: Sandflies
Leishmania parasites are transmitted by Phlebotomus (Old World) or Lutzomyia (New World) sandflies. The disease can manifest in cutaneous, mucocutaneous, or visceral forms.
Which of the following is a distinguishing feature of the phylum Ciliophora?
- A Presence of two structurally distinct nuclei
- B Exclusively autotrophic photosynthetic nutrition
- C Absence of any asexual reproduction
- D Spore formation as the primary life stage
Correct answer: Presence of two structurally distinct nuclei
Ciliates possess a large macronucleus for metabolic functions and one or more small micronuclei for genetic recombination. This nuclear dualism is a hallmark of the group.
Toxoplasmosis is most dangerous to pregnant women because the parasite can cross the placenta. The primary reservoir for Toxoplasma gondii is:
- A Domestic cats
- B Cattle
- C Rodents
- D Wild waterfowl
Correct answer: Domestic cats
Cats are the only definitive hosts where the parasite can undergo sexual reproduction and produce oocysts. Humans typically become infected through contact with cat feces or ingesting undercooked meat.
Which protozoan genus is responsible for 'Dum-Dum fever' or Kala-azar?
- A Leishmania
- B Trypanosoma
- C Plasmodium
- D Babesia
Correct answer: Leishmania
Kala-azar is the visceral form of Leishmaniasis caused by Leishmania donovani. It affects internal organs like the spleen and liver and is fatal if left untreated.
The process by which a protozoan secretes a protective wall and becomes dormant to survive harsh environmental conditions is called:
- A Encystment
- B Excystation
- C Sporogony
- D Binary fission
Correct answer: Encystment
Encystment is a survival mechanism in which the protozoan secretes a thick, resistant wall and slows its metabolism. The resulting cyst is the stage that carries many intestinal parasites from one host to the next.
In the life cycle of Plasmodium, which form is injected into the human bloodstream by a mosquito bite?
- A Gametocytes
- B Merozoites
- C Sporozoites
- D Trophozoites
Correct answer: Sporozoites
Sporozoites are the infective stage found in the salivary glands of the mosquito. Once injected, they travel to the liver to begin the exoerythrocytic cycle.