Microbiology Study Questions

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Microbiology Study Questions - Quiz

Study quesitons for Microbiology - MLT students


Questions and Answers
  • 1. 

    Protozoa are classified by their means of:

    • A.

      Reproduction

    • B.

      Locomotion

    • C.

      Respiration

    • D.

      Elimination

    Correct Answer
    B. Locomotion
    Explanation
    Protozoa are classified by their means of locomotion. This is because different types of protozoa move in different ways, such as using cilia, flagella, or pseudopodia. Locomotion is an important characteristic used to categorize and identify different species of protozoa.

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  • 2. 

    What mean of locomotion do malarial parasites have?

    • A.

      Cilia

    • B.

      Pseudopods

    • C.

      Flagella

    • D.

      None

    Correct Answer
    D. None
    Explanation
    Malarial parasites do not have any means of locomotion. This means that they are unable to move on their own and rely on other means, such as being carried by mosquitoes, to travel from one host to another.

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  • 3. 

    The Nematodes are usually found in the feces in the form of:

    • A.

      Trophozoites

    • B.

      Egg

    • C.

      Larva

    • D.

      Adult worm

    Correct Answer
    B. Egg
    Explanation
    Nematodes are commonly found in the feces in the form of eggs. Eggs are the reproductive stage of nematodes and are typically passed out of the body through feces. These eggs can then contaminate the environment and potentially infect other individuals. The other options mentioned, such as trophozoites, larva, and adult worms, are not typically found in the feces but rather in other stages of the nematode life cycle.

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  • 4. 

    Which parasite is sometimes found in the microscopic examination of urine?

    • A.

      Plasmodium

    • B.

      Tapeworm segments

    • C.

      Trichomonas

    • D.

      Yeast

    Correct Answer
    C. Trichomonas
    Explanation
    Trichomonas is a parasite that can be found in the microscopic examination of urine. It is a single-celled organism that infects the urinary tract and can cause symptoms such as itching, burning, and discharge. The presence of Trichomonas in urine can be detected through laboratory testing, where the urine sample is examined under a microscope to identify the parasite's characteristic appearance. This finding can help diagnose a Trichomonas infection and guide appropriate treatment. Plasmodium is a parasite that causes malaria and is not typically found in urine. Tapeworm segments and yeast are also not commonly seen in urine samples.

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  • 5. 

    A stool specimen should be examined immediately for:

    • A.

      Trophozoites

    • B.

      Eggs

    • C.

      Ova

    • D.

      Cyst

    Correct Answer
    A. Trophozoites
    Explanation
    A stool specimen should be examined immediately for trophozoites because trophozoites are the motile, active form of certain parasites, such as Giardia or Entamoeba histolytica. These organisms can cause gastrointestinal infections and can be easily identified and diagnosed through microscopic examination of fresh stool samples. By examining the specimen immediately, the trophozoites can be observed while they are still alive and actively moving, which helps in accurate identification and diagnosis of the infection.

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  • 6. 

    Examination of feces for trophozoites is done by:

    • A.

      Scotch tape preparation of an anal swab.

    • B.

      Wet preparation of a liquid stool

    • C.

      Macroscopic examination of stool.

    • D.

      Concentration of a formed stool.

    Correct Answer
    B. Wet preparation of a liquid stool
    Explanation
    The correct answer is wet preparation of a liquid stool. This method involves mixing a small amount of liquid stool with a drop of saline on a slide and examining it under a microscope. It allows for the detection of trophozoites, which are the active, motile form of certain parasites such as amoebae. This method is effective in identifying these organisms and is commonly used in the laboratory for diagnosing parasitic infections.

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  • 7. 

    What is a good method for finding worms or eggs?

    • A.

      2 specimens - cathartic - 1 specimen

    • B.

      1 specimen

    • C.

      Cathartic - 1 specimen

    • D.

      3 specimens

    Correct Answer
    C. Cathartic - 1 specimen
    Explanation
    Cathartic is a good method for finding worms or eggs because it helps to induce bowel movements, which can expel any worms or eggs present in the digestive system. Using a cathartic can stimulate the intestines and increase the likelihood of detecting worms or eggs in the stool sample. The presence of one specimen after using a cathartic suggests that it was effective in identifying the parasites.

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  • 8. 

    Mature cyst of Entamoeba coli usually possess a characteristic number of nuclei, which is:

    • A.

      1

    • B.

      2

    • C.

      4

    • D.

      8

    Correct Answer
    D. 8
    Explanation
    Mature cysts of Entamoeba coli typically possess 8 nuclei.

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  • 9. 

    Which of the following parasites is associated with hydatid cysts in the human?

    • A.

      Taenia saginata

    • B.

      Taenia solium

    • C.

      Diphyllobothrium latum

    • D.

      Echinococcus granulosus

    Correct Answer
    D. Echinococcus granulosus
    Explanation
    Echinococcus granulosus is associated with hydatid cysts in humans. This parasite is commonly found in dogs and other canids. Humans can become infected by ingesting the eggs of the parasite, usually through contact with contaminated soil, water, or food. Once inside the body, the eggs hatch and the larvae migrate to various organs, particularly the liver and lungs, where they form hydatid cysts. These cysts can cause a range of symptoms and complications, and if left untreated, can be life-threatening. Treatment typically involves surgical removal of the cysts and antiparasitic medications.

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  • 10. 

    The Plamodia that causes the most severe pathology is:

    • A.

      P. falciparum

    • B.

      P. vivax

    • C.

      P. malariae

    • D.

      Pm ovale

    Correct Answer
    A. P. falciparum
    Explanation
    P. falciparum is the correct answer because it is known to cause the most severe pathology among the Plasmodium species. It is responsible for the majority of malaria-related deaths worldwide. P. falciparum infection can lead to severe complications such as cerebral malaria, organ failure, anemia, and other life-threatening conditions. It has a higher propensity to infect red blood cells and can rapidly multiply, leading to more severe symptoms compared to other Plasmodium species.

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  • 11. 

    In a wet preparation of feces, iodine is used to:

    • A.

      Stain cysts

    • B.

      Decontaminate the preparation

    • C.

      Provide a background for the colorless ova

    • D.

      Stain the trophozoites

    Correct Answer
    A. Stain cysts
    Explanation
    In a wet preparation of feces, iodine is used to stain cysts. This is because iodine is a staining agent that helps to make the cysts more visible under a microscope. By staining the cysts, they can be easily identified and differentiated from other structures in the fecal sample. This is important for diagnosing certain infections and parasites that may be present in the feces.

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  • 12. 

    NIH swabs and scotch tape mounts are used to detect the ova of:

    • A.

      Whipworm

    • B.

      Roundworm

    • C.

      Pinworm

    • D.

      Hookworm

    Correct Answer
    C. Pinworm
    Explanation
    NIH swabs and scotch tape mounts are commonly used for the detection of pinworm ova. Pinworms are small, white, thread-like worms that infest the human intestines. The female pinworms lay their eggs around the anus, causing intense itching. To diagnose a pinworm infection, healthcare providers often use NIH swabs to collect samples from the perianal region and then apply scotch tape to the swabbed area. The tape is then examined under a microscope to identify any pinworm eggs present. This method is effective in detecting pinworm infections and guiding appropriate treatment.

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  • 13. 

    Tapeworms attach to the wall of the intestine by means of a:

    • A.

      Cyst

    • B.

      Larva

    • C.

      Proglottid

    • D.

      Scolex

    Correct Answer
    D. Scolex
    Explanation
    Tapeworms attach to the wall of the intestine using a structure called the scolex. The scolex is a specialized organ found at the anterior end of the tapeworm, and it contains hooks and suckers that allow the parasite to firmly attach itself to the intestinal lining. The scolex serves as an anchor for the tapeworm, allowing it to absorb nutrients from its host and complete its life cycle.

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  • 14. 

    Microscopic examination of parasites using the wet film method may use:

    • A.

      D'Antoni's solution

    • B.

      Iodine solution

    • C.

      Normal saline solution

    • D.

      All of these

    Correct Answer
    D. All of these
    Explanation
    Microscopic examination of parasites using the wet film method may use D'Antoni's solution, iodine solution, and normal saline solution. D'Antoni's solution is commonly used to stain parasites and make them more visible under the microscope. Iodine solution is used to enhance the contrast and visibility of the parasites. Normal saline solution is used to prepare the wet film and provide a suitable environment for the parasites. Therefore, all of these solutions can be used in the microscopic examination of parasites using the wet film method.

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  • 15. 

    The diagnosis of all tapeworms is made:

    • A.

      Through recognition of the ova

    • B.

      By finding and identifying gravid proglottids

    • C.

      Neither of these

    • D.

      Both of these

    Correct Answer
    D. Both of these
    Explanation
    The diagnosis of all tapeworms is made through both recognition of the ova and finding and identifying gravid proglottids. Tapeworms release eggs in the host's feces, which can be identified under a microscope. Additionally, gravid proglottids, which are segments of the tapeworm filled with eggs, can be found in the host's stool or around the anus. Therefore, both methods are used to diagnose tapeworm infections.

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  • 16. 

    In Taenia saginata, the larval stage developes in:

    • A.

      Cattle

    • B.

      Swine

    • C.

      Man

    • D.

      Fish

    Correct Answer
    A. Cattle
    Explanation
    The correct answer is cattle because Taenia saginata is a parasitic tapeworm that primarily infects cattle. The larval stage of the tapeworm develops in the muscles of cattle, where it forms cysts called cysticerci. When humans consume undercooked or raw beef infected with these cysticerci, the larvae can develop into adult tapeworms in the human intestines. Therefore, the larval stage of Taenia saginata specifically develops in cattle.

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  • 17. 

    Feces are examined for tapeworm "head" by:

    • A.

      Straining the specimen through a sieve

    • B.

      Examining wet smears of the specimen

    • C.

      Incubating the entrire specimen

    • D.

      Concentrating the specimen

    Correct Answer
    A. Straining the specimen through a sieve
    Explanation
    Straining the feces specimen through a sieve is the correct method for examining tapeworm "head". This process helps to separate the larger particles and debris from the specimen, allowing for a clearer view of any tapeworm heads that may be present. By using a sieve, the tapeworm heads can be retained while the rest of the fecal matter is strained out. This method is effective in isolating and identifying tapeworm heads for further analysis and diagnosis.

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  • 18. 

    A genus of parasites that moves about by means of pseudopods is:

    • A.

      Giardia

    • B.

      Trichomonas

    • C.

      Taenia

    • D.

      Entamoeba

    Correct Answer
    D. Entamoeba
    Explanation
    Entamoeba is the correct answer because it is a genus of parasites that are known to move by extending pseudopods, which are temporary projections of the cell membrane used for locomotion. Giardia is a genus of parasites that move by using flagella, Trichomonas is a genus of parasites that move by using flagella as well, and Taenia is a genus of parasites that are tapeworms and do not move actively. Therefore, Entamoeba is the most appropriate choice for a genus of parasites that move by means of pseudopods.

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  • 19. 

    Ascaris is a:

    • A.

      Hookworm

    • B.

      Roundworm

    • C.

      Pinworm

    • D.

      Tapeworm

    Correct Answer
    B. Roundworm
    Explanation
    Ascaris is classified as a roundworm because it belongs to the genus Ascaris, which includes several species of parasitic roundworms. These worms are characterized by their cylindrical shape and are commonly found in the intestines of humans and animals. Ascaris lumbricoides is the most common species that infects humans and can cause a condition called ascariasis. The other options mentioned, hookworm, pinworm, and tapeworm, belong to different genera and have distinct characteristics that differentiate them from roundworms.

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  • 20. 

    Only one amoeba is considered to be definitely pathogenic to man. It is:

    • A.

      Entamoeba histolytica

    • B.

      Entamoeba coli

    • C.

      Dientamoeba fragilis

    • D.

      Endolimax nana

    Correct Answer
    A. Entamoeba histolytica
    Explanation
    Entamoeba histolytica is the only amoeba that is known to be definitely pathogenic to humans. This means that it is capable of causing disease in humans. The other three amoebas listed, Entamoeba coli, Dientamoeba fragilis, and Endolimax nana, are not considered to be pathogenic to humans. They may be present in the human digestive system, but they do not typically cause disease or harm to the host. Therefore, the correct answer is Entamoeba histolytica.

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  • 21. 

    Which of the following flagellates found in the urine has no cyst form:

    • A.

      Trichomonas

    • B.

      Chilomastix

    • C.

      Giardia

    • D.

      Balantidium

    Correct Answer
    A. Trichomonas
    Explanation
    Trichomonas is the correct answer because it is a flagellate that is commonly found in the urine and does not have a cyst form. Unlike other flagellates like Giardia and Balantidium, Trichomonas does not form a protective cyst stage in its life cycle. This means that it is more susceptible to environmental conditions and is less able to survive outside of a host. Chilomastix, on the other hand, is not typically found in the urine and does have a cyst form.

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  • 22. 

    Cestodes or tapeworms consist of a series of segments know as:

    • A.

      Scolex

    • B.

      Hooklets

    • C.

      Proglottids

    • D.

      Ova

    Correct Answer
    C. Proglottids
    Explanation
    Cestodes, also known as tapeworms, are made up of a series of segments called proglottids. These proglottids contain the reproductive organs of the tapeworm and are responsible for producing eggs. Each proglottid is capable of independent movement and can release eggs into the host's digestive system. Therefore, the correct answer is "Proglottids".

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  • 23. 

    Unlike the other parasite worms, the tapeworms:

    • A.

      Exhibits packets of ova

    • B.

      Have no scolex

    • C.

      Have no alimentary tract

    • D.

      Have a reproductive system

    Correct Answer
    C. Have no alimentary tract
    Explanation
    Tapeworms are different from other parasite worms because they do not have an alimentary tract. The alimentary tract is the digestive system of an organism, which is responsible for breaking down and absorbing nutrients from food. In the case of tapeworms, they do not need to digest food themselves as they absorb nutrients directly through their body surface. This adaptation allows tapeworms to live inside the intestines of their hosts and still obtain the necessary nutrients for survival.

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  • 24. 

    The genus of parasites which causes malaria is:

    • A.

      Leishmania

    • B.

      Toxoplasma

    • C.

      Trypanosoma

    • D.

      Plasmodium

    Correct Answer
    D. Plasmodium
    Explanation
    Plasmodium is the correct answer because it is the genus of parasites that causes malaria. Malaria is a mosquito-borne infectious disease that affects humans and other animals. Plasmodium parasites are transmitted through the bite of infected female Anopheles mosquitoes. Once inside the human body, the parasites multiply in the liver and then infect red blood cells, causing the symptoms of malaria. Therefore, Plasmodium is the genus responsible for causing this disease.

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  • 25. 

    A peripheral blood smear from a patient suspected of having malaria will exhibit all but the following characteristics of infected cells:

    • A.

      Ring stages

    • B.

      Crescent-shaped gametocytes

    • C.

      Maurer's dots

    • D.

      Red cells normal size and shape

    Correct Answer
    D. Red cells normal size and shape
    Explanation
    The correct answer is "red cells normal size and shape". In a peripheral blood smear from a patient suspected of having malaria, infected cells may exhibit ring stages, crescent-shaped gametocytes, and Maurer's dots. However, one of the characteristics that would not be seen in infected cells is red cells with normal size and shape. Malaria infection can cause changes in the morphology of red blood cells, such as enlargement and distortion. Therefore, the absence of abnormal red cell morphology would suggest that malaria infection is unlikely.

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  • 26. 

    Ova of one of the follwing parasites are commonly excreted in the urine of man. Which one?

    • A.

      Taenia solium

    • B.

      Trypanosoma cruzi

    • C.

      Schistosoma hematobium

    • D.

      Fasciola hepatica

    Correct Answer
    C. Schistosoma hematobium
    Explanation
    Schistosoma hematobium is commonly excreted in the urine of humans. Schistosoma hematobium is a parasitic worm that causes urinary schistosomiasis. The adult worms live in the blood vessels around the bladder and lay eggs, which are then passed out in the urine. This is a common mode of transmission for the parasite, as the eggs can contaminate water sources and infect others who come into contact with the contaminated water. The presence of Schistosoma hematobium eggs in the urine is a key diagnostic feature of urinary schistosomiasis.

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  • 27. 

    Ova of one of the following parasites are usually found in sputum. Which one?

    • A.

      Ascaris lumbricoides

    • B.

      Metagonimus yokagawai

    • C.

      Paragonimus westermanni

    • D.

      Schistosoma hematobium

    Correct Answer
    C. Paragonimus westermanni
    Explanation
    Paragonimus westermanni is the correct answer because it is a type of lung fluke that can infect humans. The adult worms of Paragonimus westermanni reside in the lungs and lay their eggs, which are then coughed up and found in the sputum. This parasite is commonly associated with symptoms such as coughing, chest pain, and bloody sputum. Ascaris lumbricoides, Metagonimus yokagawai, and Schistosoma hematobium are not typically found in sputum.

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  • 28. 

    The ova of one of the following is characterized by the presence of a prominent lateral spine:

    • A.

      Schistosoma hematobium

    • B.

      Dyphyllobothrium latum

    • C.

      Schistosoma mansoni

    • D.

      Fasciolopsis buski

    Correct Answer
    C. Schistosoma mansoni
    Explanation
    Schistosoma mansoni is a parasitic flatworm that causes schistosomiasis in humans. The ova (eggs) of Schistosoma mansoni are characterized by the presence of a prominent lateral spine. This spine is a distinguishing feature of the ova and helps in identifying the parasite. Schistosoma hematobium, Dyphyllobothrium latum, and Fasciolopsis buski do not have this prominent lateral spine in their ova, making Schistosoma mansoni the correct answer.

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  • 29. 

    The zinc sulfate concentration method:

    • A.

      Is a sedimentation method

    • B.

      Recovers ova, larvae, and adult parasites

    • C.

      Does not recover larvae because they don't float

    • D.

      Requires formalin as a perservative.

    Correct Answer
    C. Does not recover larvae because they don't float
    Explanation
    The zinc sulfate concentration method is a sedimentation method used to recover ova, larvae, and adult parasites. However, it does not recover larvae because they do not float. This method requires formalin as a preservative.

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  • 30. 

    Which of the following is not a preservative of fecal specimens?

    • A.

      Ether

    • B.

      Formalin

    • C.

      PVA

    • D.

      MIF

    Correct Answer
    A. Ether
    Explanation
    Ether is not a preservative of fecal specimens because it is a volatile liquid that evaporates quickly. Preservatives are substances that prevent the decomposition or spoilage of specimens, but ether does not have this property. It is commonly used as a solvent or anesthetic, but it is not suitable for preserving fecal specimens.

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  • 31. 

    The genus Epidermophyton may infect:

    • A.

      Hair, nails and skin

    • B.

      Hair, nails but never skin

    • C.

      Skin, nails but never hair

    • D.

      Hair, skin but never nails

    Correct Answer
    C. Skin, nails but never hair
    Explanation
    The genus Epidermophyton is a type of fungus that commonly infects the skin and nails. It is known to cause infections such as athlete's foot and ringworm. However, it does not typically infect the hair. Therefore, the correct answer is "skin, nails but never hair".

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  • 32. 

    For more accurate stool examinations:

    • A.

      One specimen is sufficient

    • B.

      24 hour specimens are preferred.

    • C.

      3 or more fresh specimens are recommended

    • D.

      Only refrigerated specimens are acceptable

    Correct Answer
    C. 3 or more fresh specimens are recommended
    Explanation
    To ensure more accurate stool examinations, it is recommended to provide three or more fresh specimens. This is because multiple samples increase the chances of detecting any abnormalities or pathogens that may be present in the stool. Fresh specimens are preferred as they provide a more accurate representation of the current state of the gastrointestinal tract, as compared to older or preserved samples. By providing multiple fresh specimens, healthcare professionals have a better chance of identifying any potential issues or infections.

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  • 33. 

    Entamoeba histolytica is classified as a/an:

    • A.

      Amoeba

    • B.

      Flagellate

    • C.

      Ciliate

    • D.

      Sporozoa

    Correct Answer
    A. Amoeba
    Explanation
    Entamoeba histolytica is classified as an amoeba because it belongs to the phylum Amoebozoa, which includes amoebas. Amoebas are single-celled organisms that move and feed by extending pseudopods, which are temporary projections of the cell membrane. Entamoeba histolytica is a parasitic amoeba that can cause amoebic dysentery, a severe intestinal infection. Its classification as an amoeba is based on its morphological characteristics and its mode of movement.

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  • 34. 

    A common name for Dyphyllobothrium latum is the:

    • A.

      Fish tapeworm

    • B.

      Beef tapeworm

    • C.

      Pork tapeworm

    • D.

      Dwarf tapeworm

    Correct Answer
    A. Fish tapeworm
    Explanation
    The correct answer is fish tapeworm because Dyphyllobothrium latum is commonly known as the fish tapeworm. This tapeworm is primarily found in freshwater fish and can cause a condition called diphyllobothriasis in humans who consume raw or undercooked infected fish.

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  • 35. 

    Hookworm infections may be caused by:

    • A.

      Necator americanus

    • B.

      Ancylostoma duodenale

    • C.

      Both of these

    • D.

      Neither of these

    Correct Answer
    C. Both of these
    Explanation
    Hookworm infections can be caused by both Necator americanus and Ancylostoma duodenale. These are two different species of hookworms that can infect humans. Necator americanus is commonly found in the Americas, sub-Saharan Africa, and Asia, while Ancylostoma duodenale is more prevalent in the Mediterranean region, northern Africa, and parts of Asia. Both species can enter the human body through the skin and migrate to the intestines, where they attach themselves and feed on blood, causing symptoms such as anemia, abdominal pain, and diarrhea. Therefore, both Necator americanus and Ancylostoma duodenale can cause hookworm infections.

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  • 36. 

    Pinworm is the common name for:

    • A.

      Toxocara canis

    • B.

      Enterobius vermicularis

    • C.

      Fasciola hepatica

    • D.

      Fasciolopsis buski

    Correct Answer
    B. Enterobius vermicularis
    Explanation
    Enterobius vermicularis is the correct answer because it is the scientific name for pinworm, a common parasitic worm that infects the intestines of humans. Toxocara canis is the scientific name for a roundworm that infects dogs, not humans. Fasciola hepatica is the scientific name for a liver fluke that infects sheep and other animals, while Fasciolopsis buski is the scientific name for a large intestinal fluke that infects humans and pigs. Therefore, only Enterobius vermicularis corresponds to the common name "pinworm".

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  • 37. 

    The iodine stain is used to:

    • A.

      Observe motility

    • B.

      Make the nuclei prominent by staining the nuclear membrane and the karyosome

    • C.

      Distinguish trophozoites from cysts

    • D.

      Show pseudopodia

    Correct Answer
    B. Make the nuclei prominent by staining the nuclear membrane and the karyosome
    Explanation
    Iodine stain is used to make the nuclei prominent by staining the nuclear membrane and the karyosome. This staining technique helps in visualizing and distinguishing the nuclei within cells, making them more easily observable under a microscope. It does not have any effect on observing motility, distinguishing trophozoites from cysts, or showing pseudopodia.

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  • 38. 

    Candida albicans differs from other Candida species in that it:

    • A.

      Is the only pathogen for man.

    • B.

      Produce pseudomycelium

    • C.

      Assimilates carbohydrates

    • D.

      Produce chlamydoconidia on the corn meal agar

    Correct Answer
    D. Produce chlamydoconidia on the corn meal agar
    Explanation
    Candida albicans differs from other Candida species because it produces chlamydoconidia on the corn meal agar. Chlamydoconidia are thick-walled, asexual spores that are characteristic of Candida albicans and are not produced by other Candida species. This is a distinguishing feature of Candida albicans and helps to differentiate it from other species within the Candida genus.

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  • 39. 

    Thrush is caused by:

    • A.

      Candida albicans

    • B.

      Cryptococcus

    • C.

      Penicillium

    • D.

      Aspergillus

    Correct Answer
    A. Candida albicans
    Explanation
    Thrush is caused by Candida albicans, a type of yeast that is commonly found in the mouth and other parts of the body. It is a fungal infection that can occur when there is an overgrowth of this yeast. Candida albicans is known to cause various infections, including oral thrush, which is characterized by white patches on the tongue and inner cheeks. Other factors such as a weakened immune system, poor oral hygiene, or the use of certain medications can also contribute to the development of thrush.

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  • 40. 

    Nickerson's and Cornmeal agar are good media for the growth of:

    • A.

      Cryptococcus

    • B.

      Candida

    • C.

      Blastomyces

    • D.

      Histoplasma

    Correct Answer
    B. Candida
    Explanation
    Nickerson's and Cornmeal agar are good media for the growth of Candida because these agars provide the optimal conditions for the growth and development of this particular fungal species. Candida is a yeast-like fungus that requires specific nutrients and environmental factors to thrive. Nickerson's agar is a selective medium that contains inhibitors to suppress the growth of bacteria, allowing Candida to grow without competition. Cornmeal agar is a differential medium that provides essential nutrients for Candida and allows for the observation of specific morphological characteristics of the colonies. Therefore, these agars are commonly used in laboratory settings to cultivate and identify Candida species.

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  • 41. 

    A yeast has been isolated from a mouth culture. It forms germ tubes in the serum tube test. What is the genus and species of the yeast?

    • A.

      Candida albicans

    • B.

      Candida tropicalis

    • C.

      Cryptococcus neoforms

    • D.

      Torulopsis

    Correct Answer
    A. Candida albicans
    Explanation
    The yeast isolated from the mouth culture is identified as Candida albicans because it forms germ tubes in the serum tube test. Candida albicans is a common species of yeast that is often found in the mouth and other mucous membranes of humans. It is known to produce germ tubes as a characteristic feature, which helps in its identification. Other options such as Candida tropicalis, Cryptococcus neoforms, and Torulopsis do not exhibit this specific characteristic, making Candida albicans the correct answer.

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  • 42. 

    Sabouraud's agar is used to:

    • A.

      Culture animal parasites

    • B.

      Grow fungi and inhibit bacterial growth

    • C.

      Grow bacteria and inhibit fungi

    • D.

      Grow both bacteria and fungi

    Correct Answer
    B. Grow fungi and inhibit bacterial growth
    Explanation
    Sabouraud's agar is a specialized culture medium used in microbiology to grow fungi. It contains a lower pH and higher sugar concentration, creating an environment that is favorable for fungal growth while inhibiting the growth of bacteria. This selective medium helps to isolate and identify different types of fungi.

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  • 43. 

    Which of the following would be the best preparation for rapid detection of Cryptococcus neoformans in a spinal fluid?

    • A.

      Gram stain

    • B.

      10% KOH

    • C.

      India ink

    • D.

      Acid-fast stain

    Correct Answer
    C. India ink
    Explanation
    India ink is the best preparation for rapid detection of Cryptococcus neoformans in a spinal fluid. India ink is commonly used to stain the capsule of Cryptococcus neoformans, which is a key diagnostic feature of this organism. The capsule appears as a clear halo around the yeast cells when viewed under a microscope with India ink staining. This method allows for quick visualization and identification of Cryptococcus neoformans, making it the most suitable option for rapid detection in spinal fluid samples.

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  • 44. 

    Most fungi that cause systemic infections enter the body:

    • A.

      Through breaks in the skin

    • B.

      By inhalation of spores

    • C.

      By ingestion in food

    • D.

      Through the bite of a vector

    Correct Answer
    B. By inhalation of spores
    Explanation
    Fungi that cause systemic infections typically enter the body through inhalation of spores. When these spores are inhaled, they can reach the lungs and potentially spread to other organs and tissues, causing systemic infection. This mode of entry is common for many fungal pathogens, as the respiratory system provides an efficient pathway for them to enter the body. Other routes of entry, such as through breaks in the skin, ingestion in food, or through the bite of a vector, may be possible for certain fungi but are less common for systemic infections.

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  • 45. 

    The causative organism of histoplasmosis is:

    • A.

      C. neoformans

    • B.

      C. albicans

    • C.

      H. capsulatum

    • D.

      C. immitis

    Correct Answer
    C. H. capsulatum
    Explanation
    Histoplasmosis is a fungal infection caused by the organism Histoplasma capsulatum. This fungus is commonly found in soil, particularly in areas with bird or bat droppings. When the soil is disturbed, the fungal spores can become airborne and be inhaled into the lungs, causing infection. H. capsulatum is the correct answer because it is the specific causative organism for histoplasmosis. C. neoformans and C. albicans are not associated with histoplasmosis, and C. immitis is the causative organism for a different fungal infection called coccidioidomycosis.

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  • 46. 

    Actinomyces bovis is characterized by the following features except:

    • A.

      Is gram positive

    • B.

      Is aerobic

    • C.

      Is a filamentous fungus closely related to bacteria

    • D.

      Appears as granules in tissues

    Correct Answer
    B. Is aerobic
    Explanation
    Actinomyces bovis is a gram-positive, filamentous bacterium that appears as granules in tissues. Therefore, it is not aerobic.

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  • 47. 

    "Sulfur granules" are associated with:

    • A.

      Mycobacterium tuberclosis

    • B.

      Mycobacterium leprae

    • C.

      Nocardia asterodies

    • D.

      Streptomyces

    Correct Answer
    C. Nocardia asterodies
    Explanation
    Sulfur granules are associated with Nocardia asteroides. Nocardia asteroides is a species of bacteria that can cause infections in humans, particularly in the lungs, skin, and brain. These bacteria produce yellowish sulfur granules, which can be seen in the infected tissues or in pus from the abscesses. The presence of sulfur granules is a characteristic feature of Nocardia asteroides infections, helping in its identification and differentiation from other bacterial infections such as Mycobacterium tuberculosis, Mycobacterium leprae, and Streptomyces.

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  • 48. 

    Primary atypical pneumonia is caused by a:

    • A.

      Gram-positive coccus

    • B.

      Gram-positive rod

    • C.

      Gram-negative rod

    • D.

      Mycoplasma

    Correct Answer
    D. Mycoplasma
    Explanation
    Primary atypical pneumonia, also known as walking pneumonia, is caused by Mycoplasma. Mycoplasma is a type of bacteria that lacks a cell wall, making it different from other bacteria. It is classified as a gram-negative rod, and it is known to cause respiratory infections in humans. Mycoplasma pneumonia typically presents with symptoms such as a persistent cough, fever, and fatigue. Treatment usually involves antibiotics that are effective against Mycoplasma.

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  • 49. 

    One the distinguishing features of viruses is that they are:

    • A.

      Intracellular parasites

    • B.

      Gram-positive

    • C.

      Saprophytic

    • D.

      Nonpathogenic

    Correct Answer
    A. Intracellular parasites
    Explanation
    Viruses are considered intracellular parasites because they require a host cell to replicate and carry out their life cycle. They cannot reproduce or perform metabolic functions on their own. Instead, they invade host cells, hijack their cellular machinery, and use it to replicate and produce new viral particles. This dependence on host cells is a defining characteristic of viruses and sets them apart from other microorganisms.

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  • 50. 

    Viruses are obligate intracellular parasites that contain:

    • A.

      ATP-generating system

    • B.

      Ribosomes for protein synthesis

    • C.

      RNA or DNA but never both

    • D.

      All components necessary for replcation

    Correct Answer
    C. RNA or DNA but never both
    Explanation
    Viruses are obligate intracellular parasites that rely on host cells for their replication. They can contain either RNA or DNA as their genetic material, but never both at the same time. This is because viruses have evolved to specialize in either RNA or DNA-based replication strategies. The presence of both RNA and DNA in a single virus would be redundant and inefficient for their replication process. Therefore, viruses contain either RNA or DNA, depending on their specific genetic makeup and replication strategy.

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