Protozon Questions and Answers

Q: Which one of the following protozoan parasites belongs to the phylum Apicomplexa?

The apicomplexan parasite is Toxoplasma gondii.Apicomplexa are obligate intracellular parasites named after the apical complex, a group of organelles at one end of the cell used to invade host cells. The phylum also includes Plasmodium (malaria) and Cryptosporidium.The others belong to different groups. Leishmania donovani, the cause of kala-azar, is a flagellated kinetoplastid. Entamoeba histolytica is an amoeba that moves by pseudopodia. Trichomonas vaginalis is a flagellate (a parabasalid). None of them has an apical complex.

Q: Which of the following protozoa causes amoebiasis?

Amoebiasis is caused by E. histolytica, Entamoeba histolytica.The infection spreads by swallowing cysts in contaminated food or water. The trophozoites invade the wall of the large intestine, causing amoebic dysentery with flask-shaped ulcers, and can spread to the liver to form an amoebic liver abscess.Giardia intestinalis causes giardiasis, a small-intestinal infection with fatty diarrhoea. Toxoplasma gondii causes toxoplasmosis, and Trichomonas vaginalis causes trichomoniasis, a genital infection. None of these is an amoeba.

Q: Unicellular eukaryotes are grouped in

Correct answer: ProtistaProtista is the kingdom for eukaryotes that are single-celled or simple colonial forms, and it holds the protozoa along with the algae and the slime moulds. Monera and Archaea are prokaryotic, having no nucleus at all, and fungi are multicellular with chitinous walls.

Q: Which of the following organisms will vanish if all the ponds and puddles are destroyed?

Correct answer: PlasmodiumPlasmodium depends on the Anopheles mosquito, which lays its eggs in standing water, so removing every pond and puddle removes the breeding sites and breaks the transmission cycle. This is why drainage and larviciding are the oldest malaria control measures. Trypanosoma uses the tsetse fly and Leishmania the sandfly, neither of which breeds in open water.

Q: In Amoeba and Paramecium, the cell organelle for osmoregulation is

Correct answer: contractile vacuoleFresh water is hypotonic to the cell, so water enters continuously by osmosis and would burst it. The contractile vacuole collects that surplus and expels it, doing osmotic rather than excretory work - which is why marine and parasitic protozoa, living in isotonic surroundings, mostly lack one.

Q: Which class does the malarial parasite belong to?

Correct answer: sporozoaPlasmodium is placed in the Sporozoa, whose members are all parasites, have no organelle of locomotion in the adult stage, and reproduce by multiple fission producing spores. The four classes of the traditional scheme divide on exactly this point - how, or whether, the organism moves.

Q: Protozoa are classified on the basis of

Correct answer: locomotory organelleThe traditional classification turns on how the animal moves: pseudopodia in Sarcodina, flagella in Mastigophora, cilia in Ciliata, and nothing at all in Sporozoa. Shape, size and nuclear number vary too widely within each group to serve, whereas the organelle of locomotion is constant and easily observed.

Q: Organ of defense in protozoans is

Correct answer: trichocystsTrichocysts lie beneath the pellicle of Paramecium and discharge as fine threads when the animal is disturbed, serving in defence and in anchorage. Nematocysts belong to the cnidarians, and statocysts and otocysts are organs of balance in higher animals.

Q: Which of the following is not a characteristic feature of protozoans?

Correct answer: cell membrane as an outer body coveringA bare plasma membrane distinguishes nothing, since every cell has one, and many protozoa have more - a firm pellicle in Paramecium and Euglena, a shell in the foraminiferans, a test in the arcellids. Binary fission, the contractile vacuole and pseudopodia are all features the group is characterised by.

Q: Which of the following class of protozoa does not generally contain contractile vacuole?

Correct answer: SporozoaSporozoans are parasites living in the body fluids of their hosts, which are isotonic with them, so no water floods in and no organelle is needed to pump it out. The contractile vacuole is essentially a fresh water adaptation, and its absence follows directly from where these animals live.

Which one of the following protozoan parasites belongs to the phylum Apicomplexa?

A.Toxoplasma gondii
B.Leishmania donovani
C.Entamoeba histolytica
D.Trichomonas vaginalis

Exam Year(s)

IIT JAM - 2018,

Answer: A

The apicomplexan parasite is Toxoplasma gondii.

Apicomplexa are obligate intracellular parasites named after the apical complex, a group of organelles at one end of the cell used to invade host cells. The phylum also includes Plasmodium (malaria) and Cryptosporidium.

The others belong to different groups. Leishmania donovani, the cause of kala-azar, is a flagellated kinetoplastid. Entamoeba histolytica is an amoeba that moves by pseudopodia. Trichomonas vaginalis is a flagellate (a parabasalid). None of them has an apical complex.

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Which of the following protozoa causes amoebiasis?

A.Giardia intestinalis
B.E. Histolytica
C.Toxoplasma
D.Trichomonas

Exam Year(s)

RSMSSB - 2025, RSMSSB Lab Technician - 2025,

Answer: B

Amoebiasis is caused by E. histolytica, Entamoeba histolytica.

The infection spreads by swallowing cysts in contaminated food or water. The trophozoites invade the wall of the large intestine, causing amoebic dysentery with flask-shaped ulcers, and can spread to the liver to form an amoebic liver abscess.

Giardia intestinalis causes giardiasis, a small-intestinal infection with fatty diarrhoea. Toxoplasma gondii causes toxoplasmosis, and Trichomonas vaginalis causes trichomoniasis, a genital infection. None of these is an amoeba.

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Unicellular eukaryotes are grouped in

A.Monera
B.Protista
C.Archaea
D.Fungi

Answer: B

Correct answer: Protista

Protista is the kingdom for eukaryotes that are single-celled or simple colonial forms, and it holds the protozoa along with the algae and the slime moulds. Monera and Archaea are prokaryotic, having no nucleus at all, and fungi are multicellular with chitinous walls.

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Which of the following organisms will vanish if all the ponds and puddles are destroyed?

A.Plasmodium
B.Trypanosoma
C.Leishmania
D.Ascaris

Answer: A

Correct answer: Plasmodium

Plasmodium depends on the Anopheles mosquito, which lays its eggs in standing water, so removing every pond and puddle removes the breeding sites and breaks the transmission cycle. This is why drainage and larviciding are the oldest malaria control measures. Trypanosoma uses the tsetse fly and Leishmania the sandfly, neither of which breeds in open water.

Discuss in Forum

In Amoeba and Paramecium, the cell organelle for osmoregulation is

A.nucleus
B.body surface
C.contractile vacuole
D.pseudopodia

Answer: C

Correct answer: contractile vacuole

Fresh water is hypotonic to the cell, so water enters continuously by osmosis and would burst it. The contractile vacuole collects that surplus and expels it, doing osmotic rather than excretory work - which is why marine and parasitic protozoa, living in isotonic surroundings, mostly lack one.

Discuss in Forum

Which class does the malarial parasite belong to?

A.dinophyceae
B.sarcodina
C.ciliata
D.sporozoa

Answer: D

Correct answer: sporozoa

Plasmodium is placed in the Sporozoa, whose members are all parasites, have no organelle of locomotion in the adult stage, and reproduce by multiple fission producing spores. The four classes of the traditional scheme divide on exactly this point - how, or whether, the organism moves.

Discuss in Forum

Protozoa are classified on the basis of

A.locomotory organelle
B.shape
C.number of nuclei
D.size

Answer: A

Correct answer: locomotory organelle

The traditional classification turns on how the animal moves: pseudopodia in Sarcodina, flagella in Mastigophora, cilia in Ciliata, and nothing at all in Sporozoa. Shape, size and nuclear number vary too widely within each group to serve, whereas the organelle of locomotion is constant and easily observed.

Discuss in Forum

Organ of defense in protozoans is

A.statocysts
B.trichocysts
C.otocysts
D.nematocysts

Answer: B

Correct answer: trichocysts

Trichocysts lie beneath the pellicle of Paramecium and discharge as fine threads when the animal is disturbed, serving in defence and in anchorage. Nematocysts belong to the cnidarians, and statocysts and otocysts are organs of balance in higher animals.

Discuss in Forum

Which of the following is not a characteristic feature of protozoans?

A.binary fission
B.contractile vacuole
C.cell membrane as an outer body covering
D.pseudopodia

Answer: C

Correct answer: cell membrane as an outer body covering

A bare plasma membrane distinguishes nothing, since every cell has one, and many protozoa have more - a firm pellicle in Paramecium and Euglena, a shell in the foraminiferans, a test in the arcellids. Binary fission, the contractile vacuole and pseudopodia are all features the group is characterised by.

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10.

Which of the following class of protozoa does not generally contain contractile vacuole?

A.Sporozoa
B.Rhizopoda
C.Flagellata
D.Cilliata

Answer: A

Correct answer: Sporozoa

Sporozoans are parasites living in the body fluids of their hosts, which are isotonic with them, so no water floods in and no organelle is needed to pump it out. The contractile vacuole is essentially a fresh water adaptation, and its absence follows directly from where these animals live.

Discuss in Forum

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