Microbiology Exam MCQ Quiz!
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Questions and Answers
- 1.
Are the agents responsible for bovine spongiform encephalopathy (BSE) (Mad-cow disease)?
- A.
Prions
- B.
Viroids
- C.
Virus
- D.
Prokaryote
Correct Answer
A. PrionsExplanation
Prions are responsible for bovine spongiform encephalopathy (BSE), also known as Mad-cow disease. Prions are abnormal proteins that can cause normal proteins in the brain to become misfolded, leading to the development of neurological disorders. In the case of BSE, prions are believed to be transmitted through contaminated meat and can infect cattle, causing degeneration of the central nervous system. This ultimately leads to the characteristic symptoms of BSE and can be transmitted to humans through the consumption of infected meat, causing variant Creutzfeldt-Jakob disease (vCJD).Rate this question:
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- 2.
One of the following describes Yeast colonies:
- A.
Tend to spread outward and across larger areas.
- B.
Grow to a certain size and stop and limited in their diameter.
- C.
Fuzzy and fluffy or powdery in appearance.
- D.
Impart a "moldy" odor to their substrates.
Correct Answer
B. Grow to a certain size and stop and limited in their diameter.Explanation
Yeast colonies grow to a certain size and then stop growing, and their diameter is limited. This means that they do not continue to expand indefinitely like some other types of colonies.Rate this question:
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- 3.
Which one of the following is incorrect with regard to Gram +ve and Gram -ve bacteria:
- A.
In some Gram-positive bacteria glycerol–teichoic acids are bound to membrane lipids
- B.
The envelope of Gram- negative cells is a far more complicated structure than Gram +ve cells.
- C.
Under the light microscope Gram-negative cells appear purple while Gram-positive cells are red.
- D.
The Gram-positive cell wall consists primarily of a single type of molecule
Correct Answer
C. Under the light microscope Gram-negative cells appear purple while Gram-positive cells are red.Explanation
The answer is incorrect because under the light microscope, Gram-negative cells appear red while Gram-positive cells appear purple. This is due to the difference in their cell wall composition. Gram-negative bacteria have a thinner peptidoglycan layer in their cell wall, which allows the crystal violet stain to be washed out during the decolorization step, resulting in a red color when counterstained with safranin. On the other hand, Gram-positive bacteria have a thicker peptidoglycan layer that retains the crystal violet stain, giving them a purple color.Rate this question:
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- 4.
They are involved in the genetic exchange process of conjugation.
- A.
Fimbriae
- B.
Slime layers
- C.
Flagella
- D.
Pili
Correct Answer
D. PiliExplanation
Pili are involved in the genetic exchange process of conjugation. Conjugation is a mechanism by which bacteria transfer genetic material from one cell to another through direct contact. Pili, also known as sex pili, are thin, hair-like appendages that extend from the bacterial cell surface. They play a crucial role in the attachment of bacteria to other cells during conjugation, allowing for the transfer of genetic material, such as plasmids, between cells. Therefore, pili are directly involved in the genetic exchange process of conjugation.Rate this question:
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- 5.
Occur as a result of the exhaustion of essential nutrients and possibly the accumulation of bacteriostatic concentrations of wastes.
- A.
The stationary phase,
- B.
Phase A
- C.
Log phase
- D.
Phase D
Correct Answer
A. The stationary pHase,Explanation
The stationary phase occurs when essential nutrients become depleted and there is a possible build-up of bacteriostatic concentrations of wastes. This phase is characterized by a lack of growth and reproduction in the population of bacteria. It is a stage where the bacteria are not actively dividing but are still metabolically active. This phase can occur after the log phase when the bacteria have consumed all available nutrients and are unable to continue growing.Rate this question:
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- 6.
Facultative bacteria:
- A.
Bacteria cannot grow unless oxygen is present in their immediate atmosphere,
- B.
A large number of Bacteria can grow in both in the presence and absence of oxygen
- C.
None of the choices
- D.
Bacteria that inhibited in the presence of oxygen, this gas behaving almost as an intoxicant
Correct Answer
B. A large number of Bacteria can grow in both in the presence and absence of oxygenExplanation
Facultative bacteria are able to grow and survive in both aerobic (presence of oxygen) and anaerobic (absence of oxygen) conditions. This means that they have the ability to switch their metabolic pathways depending on the availability of oxygen. They can use oxygen as a terminal electron acceptor during respiration when it is present, or they can switch to fermentation or anaerobic respiration when oxygen is not available. This adaptability allows facultative bacteria to thrive in various environments, making them versatile organisms.Rate this question:
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- 7.
A key characteristic of biofilms:
- A.
Bacterial biofilms are virtually difficult to eliminate with antibiotics or biocides.
- B.
In the human body the resident cells within the biofilm are not exposed to attack by the immune system
- C.
Enveloping of the attached cells in EPS.
- D.
Biofilm formation usually begins with pioneer cells attaching to a surface
Correct Answer
C. Enveloping of the attached cells in EPS.Explanation
The correct answer is "Enveloping of the attached cells in EPS." This refers to the key characteristic of biofilms where the attached cells are surrounded and protected by a slimy matrix called extracellular polymeric substance (EPS). This EPS provides a protective barrier for the cells, making it difficult for antibiotics or biocides to penetrate and eliminate the biofilm. Additionally, the EPS also helps in the attachment of pioneer cells to a surface, initiating the biofilm formation process. In the human body, this EPS shield also prevents the immune system from effectively attacking the resident cells within the biofilm.Rate this question:
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- 8.
Is the causal organism of venereal disease gonorrhea.
- A.
Bacillus
- B.
Vibrio
- C.
Neisseria
- D.
Campylobacter
Correct Answer
C. NeisseriaExplanation
The correct answer is Neisseria. Neisseria is a genus of bacteria that includes the species Neisseria gonorrhoeae, which is the causal organism of gonorrhea. This sexually transmitted infection affects both men and women and can cause symptoms such as painful urination, discharge, and pelvic pain. Neisseria bacteria are typically found in the mucous membranes of the genital tract, throat, and rectum. They are gram-negative, diplococcal bacteria and are transmitted through sexual contact. Treatment for gonorrhea usually involves antibiotics to eliminate the infection and prevent complications.Rate this question:
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- 9.
Corynebacterium is the causal organism of:
- A.
Tuberculosis
- B.
Typhoid fever
- C.
Asiatic cholera
- D.
Diphtheria
Correct Answer
D. DipHtheriaExplanation
Corynebacterium is the causal organism of diphtheria. Diphtheria is a highly contagious bacterial infection that primarily affects the throat and nose. It is caused by the bacterium Corynebacterium diphtheriae. The bacteria produce a toxin that can damage the tissues in the respiratory system, leading to symptoms such as a sore throat, difficulty swallowing, and a thick gray coating on the back of the throat. Without proper treatment, diphtheria can be life-threatening. Vaccination is the most effective way to prevent the disease.Rate this question:
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- 10.
Is the causal organism of the tick-borne Lyme disease:
- A.
Borrelia
- B.
Mycobacterium
- C.
Salmonella
- D.
Yersinia
Correct Answer
A. BorreliaExplanation
Borrelia is the causal organism of the tick-borne Lyme disease. It is a type of bacteria that is transmitted to humans through the bite of infected black-legged ticks. These ticks are commonly found in wooded and grassy areas. Borrelia bacteria can cause a range of symptoms, including fever, fatigue, headache, muscle and joint aches, and swollen lymph nodes. If left untreated, Lyme disease can progress to more severe symptoms, affecting the joints, heart, and nervous system. Early detection and treatment with antibiotics are crucial for effectively managing Lyme disease.Rate this question:
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- 11.
One of the following dosent Gram-negative rods:
- A.
Vibrio
- B.
Treponema
- C.
Helicobacter
- D.
Haemophilus
Correct Answer
B. TreponemaExplanation
Treponema is the correct answer because it is a Gram-negative spirochete, not a Gram-negative rod. Vibrio, Helicobacter, and Haemophilus are all Gram-negative rods. Treponema, on the other hand, is a spiral-shaped bacterium and does not have the rod-like shape characteristic of Gram-negative rods.Rate this question:
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- 12.
Pseudomonas aeruginosa is resistant to many antibacterial agents.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Pseudomonas aeruginosa is known to be resistant to many antibacterial agents. This bacterium has developed various mechanisms to resist the effects of antibiotics, making it difficult to treat infections caused by this pathogen. The resistance of Pseudomonas aeruginosa to multiple antibacterial agents is a significant concern in healthcare settings and highlights the need for alternative treatment strategies.Rate this question:
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- 13.
Viruses are capable of growing on manufactured medicines or raw materials.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Viruses are not capable of growing on manufactured medicines or raw materials. Viruses require living cells to replicate and cannot reproduce outside of a host organism. Therefore, they cannot grow on non-living substances like medicines or raw materials.Rate this question:
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- 14.
The Lipid A moiety It is a very potent stimulant of the immune system.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The Lipid A moiety is indeed a very potent stimulant of the immune system. Lipid A is a component of lipopolysaccharides (LPS), which are found in the outer membrane of Gram-negative bacteria. When Lipid A is released during infection or inflammation, it can activate immune cells, such as macrophages, leading to the production of pro-inflammatory cytokines and initiation of the immune response. This immune stimulation helps to fight against bacterial infections but can also contribute to the development of sepsis or septic shock in severe cases.Rate this question:
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- 15.
Gonorrhea is a subclinical disease in males.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Gonorrhea is not a subclinical disease in males. Subclinical refers to a disease that does not show any noticeable symptoms or signs. However, gonorrhea in males often presents with symptoms such as painful urination, discharge from the penis, and swollen testicles. Therefore, it is not considered a subclinical disease in males.Rate this question:
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- 16.
Shigella is considered to be more virulent than Salmonella.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Shigella is considered to be more virulent than Salmonella because it can cause severe gastrointestinal illness, including dysentery, with a smaller infectious dose. Shigella is able to invade and multiply within the cells lining the colon, leading to more severe symptoms such as bloody diarrhea. Salmonella, on the other hand, typically causes milder symptoms and is less invasive. Therefore, Shigella is generally regarded as having a higher level of virulence compared to Salmonella.Rate this question:
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- 17.
Which of the following mainly cause the cystitis:
- A.
Bacterial capsules
- B.
Fimbriated (piliated) strains of Neisseria gonorrhoeae
- C.
Fimbriated strains of E. coli
- D.
Nonfimbriated (nonpiliated) strains of N. gonorrhoeae
Correct Answer
C. Fimbriated strains of E. coliExplanation
Fimbriated strains of E. coli mainly cause cystitis. Cystitis is an infection of the urinary bladder, and E. coli is the most common bacteria responsible for causing this infection. Fimbriae are hair-like structures on the surface of bacteria that help them attach to host cells. Fimbriated strains of E. coli have fimbriae that allow them to adhere to the lining of the bladder, leading to infection and inflammation.Rate this question:
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- 18.
Clostridium perfringens spreads deep within the body by secreting one of the following:
- A.
Coagulase
- B.
Necrotizing enzymes
- C.
Kinases
- D.
Collagenase
Correct Answer
D. CollagenaseExplanation
Clostridium perfringens spreads deep within the body by secreting collagenase. Collagenase is an enzyme that breaks down collagen, which is a major component of connective tissues in the body. By degrading collagen, Clostridium perfringens is able to invade and spread through tissues, causing further damage and infection. This mechanism allows the bacteria to penetrate deeper into the body and cause severe infections such as gas gangrene.Rate this question:
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- 19.
Which of the following mainly produce phospholipases that destroy the phagosome membrane:
- A.
Toxoplasma gondii
- B.
Rickettsia rickettsii
- C.
Protozoans
- D.
Mycobacterium tuberculosis
Correct Answer
B. Rickettsia rickettsiiExplanation
Rickettsia rickettsii mainly produces phospholipases that destroy the phagosome membrane. Phospholipases are enzymes that break down phospholipids, which are major components of cell membranes. By destroying the phagosome membrane, Rickettsia rickettsii can escape from the phagosome and avoid being destroyed by the host cell's immune response. This ability to evade the immune system is an important factor in the pathogenicity of Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever.Rate this question:
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- 20.
Biofilms and microcolonies an envelope with polysaccharide matrices.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Biofilms and microcolonies are structures formed by bacteria and other microorganisms. They consist of a community of cells that are embedded within a protective matrix made up of polysaccharides. This matrix provides structural support and protection to the microorganisms within the biofilm or microcolony. Therefore, the given statement "Biofilms and microcolonies have an envelope with polysaccharide matrices" is true.Rate this question:
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- 21.
Which of the following increases mucin production and decreases the proportion of ciliated epithelial cells:
- A.
Bile salts that contain surfactants
- B.
Inhalation of tobacco smoke
- C.
The possession of surface adhesins
- D.
Extreme acidity and presence of digestive enzymes
Correct Answer
B. Inhalation of tobacco smokeExplanation
Inhalation of tobacco smoke increases mucin production and decreases the proportion of ciliated epithelial cells. This is because tobacco smoke contains harmful chemicals that irritate the respiratory tract, leading to inflammation and damage to the cilia on the epithelial cells. The increased mucin production is a response to this irritation, as mucin helps to protect and lubricate the airways. However, the decrease in ciliated cells impairs the ability to clear mucus and foreign particles from the respiratory system, leading to respiratory problems.Rate this question:
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- 22.
Lachrymal fluids alone can enzymatically degrade the peptidoglycan of Grampositive bacteria such as staphylococci.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Lachrymal fluids cannot enzymatically degrade the peptidoglycan of Gram-positive bacteria such as staphylococci. Peptidoglycan is a major component of the bacterial cell wall, and its degradation requires specific enzymes called lysozymes. While lachrymal fluids do contain lysozymes, they are not capable of breaking down the peptidoglycan of Gram-positive bacteria. Therefore, the statement is false.Rate this question:
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- 23.
The strategy for the microorganism to kill the phagocyte can be achieved by the production of:
- A.
Endotoxin
- B.
Bile salts
- C.
Leucocidins
- D.
Lipoteichoic acids
Correct Answer
C. LeucocidinsExplanation
Leucocidins are a type of toxin produced by microorganisms that can kill phagocytes, which are immune cells responsible for engulfing and destroying pathogens. By producing leucocidins, the microorganism can evade the immune response and continue to multiply and cause infection. This strategy allows the microorganism to weaken the host's immune system and establish a foothold in the body.Rate this question:
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- 24.
Toxins that indirectly activate plasminogen:
- A.
Haemolysins
- B.
Collagenases
- C.
Hyaluronidases
- D.
Fibrinolysins
Correct Answer
D. FibrinolysinsExplanation
Fibrinolysins are toxins that indirectly activate plasminogen. Plasminogen is a precursor to plasmin, which is an enzyme involved in the breakdown of blood clots. Fibrinolysins promote the conversion of plasminogen to plasmin, leading to increased fibrinolysis and dissolution of blood clots. This indirect activation of plasminogen by fibrinolysins allows for the regulation of the fibrinolytic system and the removal of blood clots when necessary.Rate this question:
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- 25.
The number of cases of malaria in the U.S. population at this moment, that represents
- A.
The point prevalence
- B.
The period prevalence
- C.
Morbidity
- D.
The incidence of a disease
Correct Answer
A. The point prevalenceExplanation
The correct answer is "The point prevalence". Point prevalence refers to the number of cases of a disease or condition present in a population at a specific point in time. In this case, it represents the number of cases of malaria in the U.S. population at the current moment.Rate this question:
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- 26.
Malaria is endemic in a total of 101 countries and territories.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Malaria is a widespread and prevalent disease that affects many countries and territories around the world. The statement correctly states that malaria is endemic in a total of 101 countries and territories, indicating that the disease is regularly present and established in these areas. This highlights the global impact and significance of malaria as a public health concern.Rate this question:
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- 27.
One of the following is Incorrect:
- A.
The diarrheal disease relates to the feces of turtles, other reptiles
- B.
Toxoplasmosis may cause severe brain damage to the fetus when contracted by a woman during of pregnancy.
- C.
The rabies virus can be contracted by ingesting oocysts from cat feces
- D.
Cat and dog bites often transfer species of Pasteurella into tissue of human
Correct Answer
C. The rabies virus can be contracted by ingesting oocysts from cat fecesExplanation
The given statement is incorrect because rabies virus is not contracted by ingesting oocysts from cat feces. Rabies is primarily transmitted through the bite or scratch of an infected animal, usually a dog or a wild animal like a bat or raccoon. Ingesting oocysts from cat feces can lead to a parasitic infection called toxoplasmosis, not rabies.Rate this question:
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- 28.
Which of the modes of transmission can mainly include a syphilis disease :
- A.
Indirectly via arthropod vectors.
- B.
Direct mucous membrane-to-mucous membrane
- C.
Indirectly via airborne droplets
- D.
Direct skin-to-skin contact
Correct Answer
B. Direct mucous membrane-to-mucous membraneExplanation
Direct mucous membrane-to-mucous membrane transmission can mainly include a syphilis disease because syphilis is primarily transmitted through direct contact with syphilis sores or mucous membranes of an infected person during sexual activity. This mode of transmission occurs when there is direct contact between the mucous membranes of the mouth, genitals, or anus of an infected person and the mucous membranes of another person.Rate this question:
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- 29.
The typical yeast cell wall composed of glucan that can make a complex with:
- A.
Mannan
- B.
Lipids
- C.
Polysaccharides
- D.
Chitin
Correct Answer
D. ChitinExplanation
Chitin is a component that can form a complex with the typical yeast cell wall composed of glucan. Chitin is a polysaccharide that provides structural support and rigidity to the cell wall. It is commonly found in the cell walls of fungi, including yeast. By forming a complex with glucan, chitin helps to strengthen the cell wall and maintain its integrity. Mannan, lipids, and other polysaccharides may also be present in the yeast cell wall, but they do not specifically form a complex with glucan.Rate this question:
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- 30.
Which one of the following represents the Lines of ribosomes of fungal cells that strung together by a strand of mRNA?
- A.
Histones
- B.
Dermatophytes
- C.
Polysomes
- D.
Ergosterol
Correct Answer
C. PolysomesExplanation
Polysomes represent the lines of ribosomes of fungal cells that are strung together by a strand of mRNA. Polysomes are multiple ribosomes attached to a single mRNA molecule, allowing for simultaneous translation of multiple copies of the same protein. This arrangement increases the efficiency of protein synthesis in cells. Histones are proteins involved in DNA packaging, dermatophytes are a type of fungi that cause skin infections, and ergosterol is a sterol found in fungal cell membranes.Rate this question:
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- 31.
Generally presents as a problem in those with preexisting lung disease or damage.
- A.
ringworm
- B.
The mould Aspergillus fumigatus
- C.
vaginal candidosis
- D.
Nystatin
Correct Answer
B. The mould Aspergillus fumigatusExplanation
The correct answer is "The mould Aspergillus fumigatus." Generally, Aspergillus fumigatus presents as a problem in individuals who already have lung disease or damage. This mold can cause a range of respiratory symptoms and infections, particularly in people with weakened immune systems. It is important to identify and treat Aspergillus fumigatus infections promptly to prevent further complications.Rate this question:
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- 32.
Was the first azole used to treat systemic fungal infections?
- A.
Miconazole
- B.
Posaconazole
- C.
Mebendazole
- D.
Itraconazole
Correct Answer
A. MiconazoleExplanation
Miconazole is the correct answer because it was the first azole drug used to treat systemic fungal infections. Azoles are a class of antifungal drugs that work by inhibiting the growth of fungi. Miconazole was developed in the 1960s and has been used to treat various fungal infections, including systemic infections caused by Candida and Aspergillus species. It is available in various formulations, including oral, topical, and intravenous, making it versatile in its use for different types of infections.Rate this question:
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- 33.
Used topically in the treatment or prophylaxis of tinea ( ringworm)
- A.
Itraconazole
- B.
Voriconazole
- C.
Flucytosine
- D.
Tolnaftate
Correct Answer
D. TolnaftateExplanation
Tolnaftate is the correct answer because it is a medication that is used topically to treat or prevent tinea, also known as ringworm. Tinea is a fungal infection that commonly affects the skin, hair, and nails. Tolnaftate works by inhibiting the growth of the fungus, helping to eliminate the infection. It is available in various forms such as creams, powders, and sprays, making it easy to apply directly to the affected area.Rate this question:
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- 34.
Blocks the synthesis of a major fungal cell wall component 1-3-beta-D-glucan
- A.
Allylamines
- B.
Anidulafungin
- C.
Caspofungin
- D.
Polyenes
Correct Answer
C. CaspofunginExplanation
Caspofungin is the correct answer because it blocks the synthesis of a major fungal cell wall component called 1-3-beta-D-glucan. This mechanism of action inhibits the growth of fungal cells and helps to treat fungal infections. Allylamines and polyenes are other classes of antifungal drugs with different mechanisms of action. Anidulafungin is a member of the echinocandin class, which also inhibits the synthesis of 1-3-beta-D-glucan.Rate this question:
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- 35.
Shown in T.rubrum (Trichophyton rubrum) strain
- A.
Mechanisms of amphotericin B resistance
- B.
Azoles mechanism of resistance
- C.
Resistance to Terbinafine
- D.
None of the above
Correct Answer
C. Resistance to TerbinafineExplanation
The given correct answer is "Resistance to Terbinafine". This means that the mechanism being shown in T. rubrum is related to its resistance to Terbinafine, a medication commonly used to treat fungal infections. The specific details of the resistance mechanism are not provided, but it suggests that T. rubrum has developed a way to evade or counteract the effects of Terbinafine, making it less susceptible to the drug's antifungal properties.Rate this question:
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Mar 22, 2023Quiz Edited by
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Jul 19, 2020Quiz Created by
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