Clinical Microbiology Hardest Exam! Quiz

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Clinical Microbiology Hardest Exam! Quiz - Quiz


Are you ready for this Clinical Microbiology most challenging exam quiz? There are many bacteria, parasites, and viruses that attack the body in a person’s life. A microbiologist is responsible for taking samples from a patient and examining them to know the root cause of illness and come up with a diagnosis as to what one is ailing from and how to treat it. This quiz will test your understanding of some microbiology facts and act as a refresher to know what to read on.


Questions and Answers
  • 1. 

    Staphylococcus is...

    • A.

      Facultatively aerobic

    • B.

      Facultatively anaerobic

    • C.

      Obligate aerobe

    • D.

      Obligate anaerobe

    Correct Answer
    B. Facultatively anaerobic
    Explanation
    Staphylococcus is classified as facultatively anaerobic because it has the ability to grow and survive in both the presence and absence of oxygen. This means that it can switch between aerobic respiration when oxygen is available and fermentation or anaerobic respiration when oxygen is not available. Staphylococcus is a versatile bacterium that can adapt to different environments, making it capable of causing infections in various parts of the body.

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  • 2. 

    Name one Invasin used by Vibrio Cholerae and Shigella dysenteriae

    • A.

      Neuraminidase

    • B.

      Hyaluronidase

    • C.

      Collagenase

    • D.

      Option 4

    Correct Answer
    A. Neuraminidase
    Explanation
    Neuraminidase is an enzyme used by both Vibrio Cholerae and Shigella dysenteriae as an invasin. It helps these bacteria invade and colonize the host cells by breaking down the protective mucous layer that covers the surface of the cells. By breaking down this layer, the bacteria can attach to and penetrate the host cells more easily, leading to infection.

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  • 3. 

    All of the following are Invasins used by Clostridium perfringens EXCEPT

    • A.

      Collagenase that breaks down the framework of muscles, which facilitates gas gangrene

    • B.

      Streptokinase that convrt plasminogen to plasmin

    • C.

      Phospholipases that hydrolyze phospholipids in cell membranes by removal of polar head groups

    • D.

      Hyaluronidase that attacks the interstitial cement of connective tissue by depolymerizing hyaluronic acid

    Correct Answer
    B. Streptokinase that convrt plasminogen to plasmin
    Explanation
    Streptokinase is not an invasin used by Clostridium perfringens. Invasins are proteins produced by bacteria that aid in their invasion and spread within the host's tissues. Collagenase, phospholipases, and hyaluronidase are all invasins used by Clostridium perfringens. Collagenase breaks down the framework of muscles, facilitating gas gangrene. Phospholipases hydrolyze phospholipids in cell membranes. Hyaluronidase attacks the interstitial cement of connective tissue by depolymerizing hyaluronic acid. However, streptokinase is not produced by Clostridium perfringens and does not play a role in its invasion or spread.

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  • 4. 

    Where is Staphylococcus epidermidis found?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Colon

    • H.

      Distal urethra

    • I.

      Vagina

    Correct Answer(s)
    A. Skin
    B. Conjunctiva
    C. Ear
    D. Nasopharynx
    E. Oropharynx
    H. Distal urethra
    Explanation
    Staphylococcus epidermidis is a type of bacteria that is commonly found on the skin, in the ears, on the conjunctiva (the membrane that covers the front of the eye and lines the inside of the eyelids), in the nasopharynx (the upper part of the throat behind the nose), in the oropharynx (the middle part of the throat behind the mouth), and in the distal urethra (the end part of the urethra, which is the tube that carries urine out of the body). It is not typically found in the small intestine, colon, or vagina.

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  • 5. 

    Where is Bacteroides found?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Colon

    • H.

      Distal Urethra

    • I.

      Vagina

    Correct Answer(s)
    E. Oropharynx
    F. Small intestine
    G. Colon
    H. Distal Urethra
    I. Vagina
    Explanation
    Bacteroides is a genus of bacteria that is commonly found in various parts of the human body. It is known to be present in the colon, which is the largest part of the large intestine. Bacteroides can also be found in the small intestine, which is the part of the digestive system located between the stomach and the large intestine. Additionally, Bacteroides can be found in the oropharynx, which is the part of the throat that is behind the mouth and nasal cavity. It can also be found in the vagina, which is the internal reproductive organ in females. Finally, Bacteroides can be found in the distal urethra, which is the part of the urethra that is closest to the external opening.

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  • 6. 

    Where is Staph aureus found?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Outer ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Large intestine

    • H.

      Distal urethra

    • I.

      Vagina

    Correct Answer(s)
    A. Skin
    B. Conjunctiva
    D. Nasopharynx
    E. Oropharynx
    F. Small intestine
    G. Large intestine
    Explanation
    Staph aureus can be found in various locations in the body including the skin, conjunctiva (the mucous membrane that covers the front of the eye and lines the inside of the eyelids), nasopharynx (the upper part of the throat behind the nose), oropharynx (the middle part of the throat behind the mouth), large intestine, and small intestine. These locations provide suitable environments for the growth and colonization of Staph aureus.

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  • 7. 

    Where is Lactobacillus usually found?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Colon

    • H.

      Distal urethra

    • I.

      Vagina

    Correct Answer(s)
    E. Oropharynx
    F. Small intestine
    G. Colon
    H. Distal urethra
    I. Vagina
    Explanation
    Lactobacillus is usually found in various parts of the body, including the small intestine, colon, oropharynx, distal urethra, vagina, and even on the skin, nasopharynx, conjunctiva, and ear. These locations are known to have a microbiota that includes Lactobacillus, which helps maintain the balance of bacteria and supports various physiological functions in these areas.

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  • 8. 

    Where does Pseudomonas normally cause infection?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Outer ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Colon

    • H.

      Distal urethra

    • I.

      Vagina

    Correct Answer
    C. Outer ear
    Explanation
    Pseudomonas normally causes infection in the outer ear. This is known as otitis externa or swimmer's ear. It is an infection of the ear canal, typically caused by water remaining in the ear after swimming or bathing, creating a moist environment where Pseudomonas can thrive. Symptoms include pain, itching, redness, and discharge from the ear. Treatment usually involves antibiotic ear drops and keeping the ear dry.

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  • 9. 

    Where does Streptococcus pneumonia normally cause infection?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Outer ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Large intestine

    • H.

      Distal urethra

    • I.

      Vagina

    Correct Answer(s)
    D. Nasopharynx
    E. Oropharynx
    Explanation
    Streptococcus pneumoniae normally causes infection in the oropharynx and nasopharynx. These are the areas where the bacteria commonly reside and can cause infections such as pneumonia, sinusitis, and ear infections. The bacteria can be transmitted through respiratory droplets and can colonize in these areas, leading to infection if the immune system is compromised or if the bacteria overgrow.

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  • 10. 

    Which requires anaerobic coverage in the colon?

    • A.

      Bacteroides

    • B.

      Clostridium

    • C.

      Fusobacterium

    • D.

      Peptostreptococcus

    • E.

      Corynebacterium

    • F.

      Pseudomonas

    • G.

      Enterobacteriacae

    Correct Answer(s)
    A. Bacteroides
    B. Clostridium
    C. Fusobacterium
    D. Peptostreptococcus
    Explanation
    Bacteroides, Clostridium, Fusobacterium, and Peptostreptococcus all require anaerobic coverage in the colon. These bacteria are part of the normal flora of the colon and thrive in an environment with little to no oxygen. They play important roles in the breakdown of complex carbohydrates and the production of short-chain fatty acids. Anaerobic coverage is necessary to target and eliminate these bacteria in case of infection or overgrowth, as they can cause serious diseases such as abscesses, sepsis, and colitis.

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  • 11. 

    Which requires anaerobic coverage in the small intestine?

    • A.

      Lactobacillus

    • B.

      Fusobacterium

    • C.

      Peptostreptococcus

    • D.

      Clostridium

    • E.

      E. Coli

    • F.

      Bacteroides

    • G.

      Enterococcus

    Correct Answer(s)
    B. Fusobacterium
    C. Peptostreptococcus
    D. Clostridium
    F. Bacteroides
  • 12. 

    Which requires Anaerobic coverage in the oropharynx?

    • A.

      Eikenella corrodens

    • B.

      Peptostreptococcus

    • C.

      Moraxella Catarrhalis

    • D.

      Fusobacterium

    • E.

      Bacteroides

    • F.

      Actinomyces

    • G.

      Viridans Strep

    Correct Answer(s)
    B. Peptostreptococcus
    D. Fusobacterium
    E. Bacteroides
    F. Actinomyces
    Explanation
    Peptostreptococcus, Fusobacterium, Bacteroides, and Actinomyces are all anaerobic bacteria that can be found in the oropharynx. These bacteria do not require oxygen to survive and can thrive in environments with low oxygen levels. They are commonly associated with infections in the oral cavity and can cause conditions such as dental abscesses, periodontal disease, and tonsillitis. Therefore, anaerobic coverage is necessary to effectively treat infections caused by these bacteria in the oropharynx.

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  • 13. 

    What is a common cause of infection in the nasopharynx?

    • A.

      Staph aureus

    • B.

      Strep pneumonia

    • C.

      Staph epidermidis

    • D.

      Haemophilus

    • E.

      Niesseria

    Correct Answer(s)
    A. Staph aureus
    B. Strep pneumonia
    Explanation
    Staph aureus and Strep pneumonia are both common causes of infection in the nasopharynx. Staph aureus is a bacterium that can cause various infections, including respiratory infections, while Strep pneumonia is a leading cause of bacterial pneumonia and can also infect the upper respiratory tract. Both bacteria can easily spread through respiratory droplets, making them common culprits for nasopharyngeal infections. Staph epidermidis, Haemophilus, and Niesseria are also bacteria that can cause infections, but they are not as commonly associated with nasopharyngeal infections as Staph aureus and Strep pneumonia.

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  • 14. 

    What commonly cause infection in the small intestine?

    • A.

      Bacteroides

    • B.

      Enterococcus

    • C.

      Fusobacterium

    • D.

      Peptostreptococcus

    • E.

      Candidia

    • F.

      Clostridium

    • G.

      Enterobacteriacae

    Correct Answer(s)
    A. Bacteroides
    E. Candidia
    F. Clostridium
    G. Enterobacteriacae
    Explanation
    Bacteroides, Candidia, Clostridium, and Enterobacteriaceae commonly cause infection in the small intestine. These microorganisms are known to be opportunistic pathogens that can cause various types of infections, including gastrointestinal infections. Bacteroides is a normal part of the gut microbiota but can cause infection if it overgrows or enters other parts of the body. Candida is a type of yeast that can cause infections, particularly in individuals with weakened immune systems. Clostridium is a genus of bacteria that includes several species known to cause intestinal infections, such as Clostridium difficile. Enterobacteriaceae is a family of bacteria that includes many common pathogens, such as Escherichia coli and Salmonella, which can cause intestinal infections.

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  • 15. 

    What are the common causes of infection in the oropharynx?

    • A.

      Moraxella catarrhalis

    • B.

      Viridans strep

    • C.

      Actinomyces

    • D.

      Neisseria

    • E.

      Staph aureus

    • F.

      Strep Pyogenes

    • G.

      Strep pneumoniae

    • H.

      Haemophilus influenz

    • I.

      Bacteroides

    Correct Answer(s)
    A. Moraxella catarrhalis
    B. Viridans strep
    E. Staph aureus
    F. Strep Pyogenes
    G. Strep pneumoniae
    H. Haemophilus influenz
    Explanation
    The common causes of infection in the oropharynx include Moraxella catarrhalis, Viridans strep, Staph aureus, Strep Pyogenes, Strep pneumoniae, Haemophilus influenzae, Neisseria, Bacteroides, and Actinomyces. These organisms are commonly found in the oropharynx and can cause various infections such as tonsillitis, pharyngitis, and abscesses. It is important to identify the causative organism in order to provide appropriate treatment.

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  • 16. 

    Which commonly cause infection in the colon?

    • A.

      Bacterioides

    • B.

      Clostridium

    • C.

      Enterobacteriaceae

    • D.

      Enterococcus

    • E.

      Fusobacterium

    • F.

      Peptostreptococcus

    • G.

      Lactobacillus

    • H.

      Corynebacterium

    • I.

      Mycobacterium

    • J.

      Candidia

    Correct Answer(s)
    A. Bacterioides
    B. Clostridium
    C. Enterobacteriaceae
    D. Enterococcus
    E. Fusobacterium
    F. Peptostreptococcus
    J. Candidia
    Explanation
    The given correct answer includes several types of bacteria and fungi that commonly cause infection in the colon. Bacteroides, Clostridium, Enterobacteriaceae, Enterococcus, Fusobacterium, Peptostreptococcus, and Candida are all known to be pathogens that can infect the colon. These microorganisms can cause various types of infections such as colitis, diverticulitis, and other gastrointestinal disorders. It is important to identify and treat these infections promptly to prevent further complications.

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  • 17. 

    What commonly causes infection in the distal urethra?

    • A.

      Gardnerella vaginalis

    • B.

      Enterobacteriaceae

    • C.

      Enterococcus

    • D.

      Mycoplasma

    • E.

      Ureaplasma

    • F.

      Candidia

    • G.

      Bacterioides

    • H.

      Neisseria

    Correct Answer(s)
    B. Enterobacteriaceae
    D. Mycoplasma
    E. Ureaplasma
    F. Candidia
    Explanation
    Infection in the distal urethra can be commonly caused by Enterobacteriaceae, Mycoplasma, Ureaplasma, and Candidia. These are all types of bacteria and fungi that can infect the urethra and cause symptoms such as pain, burning sensation during urination, and discharge. These microorganisms can enter the urethra through sexual activity, poor hygiene, or other means of contamination. It is important to identify and treat the specific causative agent to effectively manage the infection.

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  • 18. 

    Where is Corynebacterium found?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Colon

    • H.

      Distal Urethra

    • I.

      Vagina

    Correct Answer(s)
    D. Nasopharynx
    E. Oropharynx
    G. Colon
    H. Distal Urethra
    Explanation
    Corynebacterium can be found in various locations in the human body, including the distal urethra, colon, oropharynx, and nasopharynx. These bacteria are part of the normal flora in these areas and do not typically cause harm. The presence of Corynebacterium in these locations is important for maintaining a healthy microbial balance and preventing the overgrowth of harmful bacteria.

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  • 19. 

    Which of the following cause premature dissociation of peptidyl-tRNA from the ribosome?

    • A.

      Glycylcyclines

    • B.

      Macrolides

    • C.

      Mupirocin

    • D.

      Rifampin

    • E.

      Chloramphenicol

    • F.

      Clindamycin

    • G.

      Streptogramins

    • H.

      Linezolid

    • I.

      Ketolides

    • J.

      Aminoglycosides

    • K.

      Tetracyclines

    Correct Answer(s)
    B. Macrolides
    F. Clindamycin
    G. Streptogramins
    Explanation
    Macrolides, clindamycin, and streptogramins cause premature dissociation of peptidyl-tRNA from the ribosome. These antibiotics bind to the 50S subunit of the bacterial ribosome, inhibiting the translocation step of protein synthesis. This prevents the elongation of the polypeptide chain and leads to premature dissociation of the peptidyl-tRNA from the ribosome. This disruption in protein synthesis ultimately inhibits bacterial growth and helps in the treatment of bacterial infections.

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  • 20. 

    How does Mupirocin function?

    • A.

      Binds to 23s rRNA of 50s Subunit, inhibiting the formation of ribosome mRNA complex

    • B.

      Blocks ribosomal exit tunnel, terminating peptide synthesis

    • C.

      Inhibits isoleucine synthetase, preventing it from binding to tRNA to be incorporated into the peptie chairn

    • D.

      Irreversibly binds 50s subunit, inhibiting peptidyl transferase

    • E.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis

    Correct Answer
    C. Inhibits isoleucine synthetase, preventing it from binding to tRNA to be incorporated into the peptie chairn
    Explanation
    Mupirocin functions by inhibiting isoleucine synthetase, which is an enzyme responsible for binding isoleucine to tRNA. By preventing this binding, mupirocin prevents the incorporation of isoleucine into the growing peptide chain during protein synthesis. This ultimately disrupts the normal functioning of bacterial cells and inhibits their growth.

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  • 21. 

    How does Linezolid function?

    • A.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site

    • B.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis

    • C.

      Reversibly binds the 23s rRNA of the 50s subunit, inhibiting the formation of the ribosome-mRNA complex

    • D.

      Reversibly binds the 50s subunit inhibiting translocatio of tRNA from A site to P site

    Correct Answer
    C. Reversibly binds the 23s rRNA of the 50s subunit, inhibiting the formation of the ribosome-mRNA complex
  • 22. 

    How do Macrolides function?

    • A.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis

    • B.

      Reversibly bind the 50s subunit, preventing peptidyl transferase activity, inhibiting the translocation of tRNA from A site to P site

    • C.

      Prevents peptide bond formation during elongation

    • D.

      Binds to RNA Polymerase inhibiting the initiation of trasncription

    Correct Answer
    B. Reversibly bind the 50s subunit, preventing peptidyl transferase activity, inhibiting the translocation of tRNA from A site to P site
    Explanation
    Macrolides function by reversibly binding to the 50s subunit of the ribosome. This binding prevents the peptidyl transferase activity, which is responsible for the formation of peptide bonds during protein synthesis. Additionally, the binding inhibits the translocation of tRNA from the A site to the P site, interrupting the elongation of protein synthesis.

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  • 23. 

    How do Clindamycin and other Lincosamides function?

    • A.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis

    • B.

      Irreversibly binds the 50s subunit preventing peptide bond formation during elongation

    • C.

      Reversibly bind the 50s subunit, inhibiting translocation of tRNA from A site to P site, causing premature dissociation of the peptidyl-tRNA from the ribosome

    • D.

      Energy dependent, sometimes irreversible finding to the 30s subunit, disrupting the formation of ribosome-mRNA complex. causing errors in translation, and blocks translocation

    Correct Answer
    C. Reversibly bind the 50s subunit, inhibiting translocation of tRNA from A site to P site, causing premature dissociation of the peptidyl-tRNA from the ribosome
    Explanation
    Clindamycin and other Lincosamides function by reversibly binding to the 50s subunit of the ribosome. This binding inhibits the translocation of tRNA from the A site to the P site, which leads to the premature dissociation of the peptidyl-tRNA from the ribosome. This disruption in the normal process of translocation and elongation of protein synthesis ultimately inhibits bacterial growth and replication.

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  • 24. 

    How do Streptogramins work?

    • A.

      Irreversibly bind to the 50s subunit . Group A prevents peptide bond formation during elongation. Group B causes premature dissociation of peptidyl-tRNA from the ribosome

    • B.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis

    • C.

      Binds to 30s, sometimes irreversibly, disrupting the formation of ribosome-mRNA complex, causes errors in translation, and blocks translocation

    • D.

      Reversibly binds to the 23s rRNA of the 50s subunit, inhibiting the formation of the ribosome-mRNA complex

    Correct Answer
    A. Irreversibly bind to the 50s subunit . Group A prevents peptide bond formation during elongation. Group B causes premature dissociation of peptidyl-tRNA from the ribosome
    Explanation
    Streptogramins work by irreversibly binding to the 50s subunit of the ribosome. Group A of streptogramins prevents peptide bond formation during elongation, while Group B causes premature dissociation of peptidyl-tRNA from the ribosome. This disruption in the ribosome's function ultimately inhibits protein synthesis.

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  • 25. 

    How do Ketolides function?

    • A.

      Blocks the ribosomal exit tunnel, thus terminating peptide synthesis

    • B.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis

    • C.

      Reversibly binds to the 23s rRNA of the 50s subunit, inhibiting the formation of the ribosome-mRNA complex

    • D.

      Binds to the 50s subunit, inhibiting translocation of tRNA from A site to P site, causing premature dissociation of peptidyl-tRNA from the ribosome

    Correct Answer
    A. Blocks the ribosomal exit tunnel, thus terminating peptide synthesis
    Explanation
    The correct answer states that ketolides function by blocking the ribosomal exit tunnel, which leads to the termination of peptide synthesis. This means that ketolides prevent the newly synthesized peptide from being released from the ribosome, ultimately stopping the process of protein synthesis.

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  • 26. 

    How does Chloramphenicol function?

    • A.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis

    • B.

      Irreversibly binds to the 50s subunit, inhibiting peptidyl transferase

    • C.

      Energy-dependent, sometimes irreversible binding to the 30s subunit, disrupting the formation of the ribosome-mRNA complex, causing errors in translation, blocking translocation

    • D.

      Blocks the ribosomal exit tunnel, terminating peptide synthesis

    Correct Answer
    B. Irreversibly binds to the 50s subunit, inhibiting peptidyl transferase
    Explanation
    Chloramphenicol functions by irreversibly binding to the 50s subunit of the ribosome. This binding inhibits the activity of peptidyl transferase, an enzyme responsible for forming peptide bonds during protein synthesis. By inhibiting this enzyme, chloramphenicol effectively prevents the elongation of protein synthesis.

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  • 27. 

    How do Aminoglycosides function?

    • A.

      Energy dependent, sometimes irreversible binding to the 30s subunit, disrupting the formation of the ribosome-mRNA complex, causes errors in translation, blocking translocation

    • B.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of prrotein synthesis

    • C.

      Reversibly binds to the 23s rRNA of the 50s subunit, inhibiting the formation of the ribosome-mRNA complex

    • D.

      Reversibly binds to bacterial isoleucyl-tRNA synthetase, inhibiting this enzyme keeps isoleucine from being added to the forming protein

    Correct Answer
    A. Energy dependent, sometimes irreversible binding to the 30s subunit, disrupting the formation of the ribosome-mRNA complex, causes errors in translation, blocking translocation
    Explanation
    Aminoglycosides function by binding to the 30s subunit of the ribosome in an energy-dependent manner. This binding can sometimes be irreversible and disrupts the formation of the ribosome-mRNA complex. As a result, errors in translation occur and translocation, the movement of the ribosome along the mRNA strand, is blocked. This ultimately leads to the inhibition of protein synthesis.

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  • 28. 

    How do Tetracyclines and Glycylcyclines function?

    • A.

      Energy dependent, sometimes irreversible, binding to the 30s subunit, disrupting the formation of the ribosome-mRNA cmoplex, causing errors in translation, blocks translocation

    • B.

      Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis

    • C.

      Irreversibly binds to the 50s subunit, preventing peptide bond formation during elongation, causing premature dissociation of peptidyl-tRNA from the ribosome

    • D.

      Reversibly bidns to the 50s subunit, inhibiting translocation of tRNA from A site to P site, causing premature dissociation of peptidyl-tRNA from the ribosome

    Correct Answer
    B. Binds to 30s subunit and inhibits binding of aminoacyl-tRNA to the A site, interrupting elongation of protein synthesis
    Explanation
    Tetracyclines and Glycylcyclines function by binding to the 30s subunit of the ribosome. This binding inhibits the binding of aminoacyl-tRNA to the A site, which is necessary for the elongation of protein synthesis. As a result, the process of translation is interrupted, leading to errors in protein synthesis. This explanation aligns with the given answer option.

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  • 29. 

    Function of Helicase

    • A.

      Unwinds the DNA chain after topoisomerase has done its thing

    • B.

      Reverses the twists to relax the stress on the DNA strand

    Correct Answer
    A. Unwinds the DNA chain after topoisomerase has done its thing
    Explanation
    Helicase is an enzyme that plays a crucial role in DNA replication. It unwinds the double-stranded DNA molecule by breaking the hydrogen bonds between the base pairs, allowing the two strands to separate. This process occurs after topoisomerase has relieved the tension in the DNA molecule by cutting and rejoining the strands. By unwinding the DNA chain, helicase prepares the template strands for the binding of DNA polymerase and the synthesis of new DNA strands during replication. Therefore, the correct answer states that helicase unwinds the DNA chain after topoisomerase has completed its function.

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  • 30. 

    Function of DNA Gryrase

    • A.

      Reverses the twists to relax the stress on the DNA strand

    • B.

      Unwinds the DNA supercoil so that Helicase can do its thing

    Correct Answer
    A. Reverses the twists to relax the stress on the DNA strand
    Explanation
    DNA gyrase is an enzyme that plays a crucial role in DNA replication and maintenance. It is responsible for reversing the twists in the DNA strand, thereby relieving the stress caused by the coiling of the DNA molecule. This action allows the DNA to unwind and become more relaxed, making it easier for other enzymes, such as helicase, to access the DNA and perform their respective functions. By reversing the twists and reducing the tension in the DNA strand, DNA gyrase helps to ensure efficient DNA replication and transcription processes.

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  • 31. 

    Function of Metronidazole

    • A.

      Structurally similar to PABA so they competitively bind to dihydropteroate synthase, thus preveting synthesis of DNA and proteins

    • B.

      Blocks the production of tetrahydrofolic acid by binding to and reversibly inhibiting dihydrofolate reductase

    • C.

      In an anaerobic environment, passively diffuses into cytoplasm of bacteria and is reduced to form nitroso free radical that interacts with DNA, inhibiting its synthesis and causinff its fragmentation, leading to death of the bacteria

    • D.

      Inhibit DNA Gyrase, leading to fracturing of the DNA and bacterial cell death, targeting Gram – bacteria. Targets Gram + bacteria by inhibiting Topoisomerasae IV, preventing the separation of daughter strands, fracturing DNA

    Correct Answer
    C. In an anaerobic environment, passively diffuses into cytoplasm of bacteria and is reduced to form nitroso free radical that interacts with DNA, inhibiting its synthesis and causinff its fragmentation, leading to death of the bacteria
    Explanation
    Metronidazole functions by passively diffusing into the cytoplasm of bacteria in an anaerobic environment. Once inside, it is reduced to form a nitroso free radical. This free radical then interacts with the DNA of the bacteria, inhibiting its synthesis and causing fragmentation. As a result, the bacteria are unable to replicate and eventually die. This mechanism of action specifically targets anaerobic bacteria.

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  • 32. 

    Function of Dapsone

    • A.

      Blocks the production of tetrahydrofolic acid by binding to and reversibly inhibiting dihydrofolate reductase

    • B.

      In an anaerobic environment, passively diffuses into cytoplasm of bacteria and is reduced to form nitroso free radical that interacts with DNA, inhibiting its synthesis and causing its fragmentation, leading to death of the bacteria

    • C.

      Structurally similar to PABA so they competitively bind to dihydropteroate synthase, thus preveting synthesis of DNA and proteins

    Correct Answer
    C. Structurally similar to PABA so they competitively bind to dihydropteroate synthase, thus preveting synthesis of DNA and proteins
    Explanation
    Dapsone functions by competitively binding to dihydropteroate synthase, which is involved in the synthesis of DNA and proteins. This structural similarity to PABA allows dapsone to effectively block the enzyme's activity, preventing the production of DNA and proteins. This inhibition of essential cellular processes ultimately leads to the death of bacteria.

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  • 33. 

    Function of Sulfonamides

    • A.

      In an anaerobic environment, passively diffuses into cytoplasm of bacteria and is reduced to form nitroso free radical that interacts with DNA, inhibiting its synthesis and causing its fragmentation, leading to death of the bacteria

    • B.

      Structurally similar to PABA so they competitively bind to dihydropteroate synthase, thus preveting synthesis of DNA and proteins

    • C.

      Blocks the production of tetrahydrofolic acid by binding to and reversibly inhibiting dihydrofolate reductase

    • D.

      Inhibit DNA Gyrase, leading to fracturing of the DNA and bacterial cell death, targeting Gram – bacteria. Targets Gram + bacteria by inhibiting Topoisomerasae IV, preventing the separation of daughter strands, fracturing DNA

    Correct Answer
    B. Structurally similar to PABA so they competitively bind to dihydropteroate synthase, thus preveting synthesis of DNA and proteins
    Explanation
    Sulfonamides are structurally similar to PABA (para-aminobenzoic acid), and they function by competitively binding to dihydropteroate synthase. This binding prevents the synthesis of DNA and proteins. By inhibiting this enzyme, sulfonamides interfere with the production of tetrahydrofolic acid, an essential component for DNA synthesis. This disruption in DNA synthesis ultimately leads to the death of bacteria.

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  • 34. 

    Function of Trimethoprim

    • A.

      Structurally similar to PABA so they competitively bind to dihydropteroate synthase, thus preveting synthesis of DNA and proteins

    • B.

      Blocks the production of tetrahydrofolic acid by binding to and reversibly inhibiting dihydrofolate reductase

    • C.

      In an anaerobic environment, passively diffuses into cytoplasm of bacteria and is reduced to form nitroso free radical that interacts with DNA, inhibiting its synthesis and causing its fragmentation, leading to death of the bacteria

    • D.

      Inhibit DNA Gyrase, leading to fracturing of the DNA and bacterial cell death, targeting Gram – bacteria. Targets Gram + bacteria by inhibiting Topoisomerasae IV, preventing the separation of daughter strands, fracturing DNA

    Correct Answer
    B. Blocks the production of tetrahydrofolic acid by binding to and reversibly inhibiting dihydrofolate reductase
    Explanation
    Trimethoprim functions by blocking the production of tetrahydrofolic acid, which is essential for the synthesis of DNA and proteins in bacteria. It achieves this by binding to and reversibly inhibiting the enzyme dihydrofolate reductase. This inhibition disrupts the folate pathway, preventing the synthesis of tetrahydrofolic acid and ultimately inhibiting bacterial growth. By targeting this specific enzyme, trimethoprim selectively affects bacteria without harming human cells, making it an effective antibiotic for treating bacterial infections.

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  • 35. 

    In what order do these occur?

    • A.

      Topoisomerase-->Gyrase-->Tetrahydrofolic Acid-->RNA Polymerase-->DNA Polymerase-->DNA Ligase-->Helicase-->Topoisomerase IV

    • B.

      Topoisomerase IV-->Helicase-->Tetrahydrofolic Acid-->RNA Polymerase-->DNA Polymerase-->DNA Ligase-->DNA Gyrase-->Topoisomerases

    • C.

      Topoisomerase-->Helicase-->Tetrahydrofolic Acid-->RNA Polymerase-->DNA Polymerase-->DNA Ligase-->DNA Gyrase-->Topoisomerase IV

    • D.

      Topoisomerase II-->Helicase-->Tetrahydrofolic Acid-->RNA Polymerase-->DNA polymerase-->DNA ligase--> DNA Gyrase-->Topoisomerase IV

    Correct Answer
    C. Topoisomerase-->Helicase-->Tetrahydrofolic Acid-->RNA Polymerase-->DNA Polymerase-->DNA Ligase-->DNA Gyrase-->Topoisomerase IV
    Explanation
    The correct order of these events is as follows: Topoisomerase, Helicase, Tetrahydrofolic Acid, RNA Polymerase, DNA Polymerase, DNA Ligase, DNA Gyrase, and Topoisomerase IV. Topoisomerase is responsible for relieving the tension in the DNA helix, followed by Helicase which unwinds the DNA strands. Tetrahydrofolic Acid is involved in the synthesis of nucleotides, while RNA Polymerase transcribes DNA into RNA. DNA Polymerase then synthesizes new DNA strands, and DNA Ligase joins the fragments together. DNA Gyrase helps in the supercoiling of DNA, and Topoisomerase IV separates the DNA strands after replication.

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  • 36. 

    Function of Fluoroquinolones

    • A.

      Blocks the production of tetrahydrofolic acid by binding to and reversibly inhibiting dihydrofolate reductase

    • B.

      Structurally similar to PABA so they competitively bind to dihydropteroate synthase, thus preveting synthesis of DNA and proteins

    • C.

      Inhibit DNA Gyrase, leading to fracturing of the DNA and bacterial cell death, targeting Gram – bacteria. Targets Gram + bacteria by inhibiting Topoisomerasae IV, preventing the separation of daughter strands, fracturing DNA

    • D.

      In an anaerobic environment, passively diffuses into cytoplasm of bacteria and is reduced to form nitroso free radical that interacts with DNA, inhibiting its synthesis and causing its fragmentation, leading to death of the bacteria

    Correct Answer
    C. Inhibit DNA Gyrase, leading to fracturing of the DNA and bacterial cell death, targeting Gram – bacteria. Targets Gram + bacteria by inhibiting Topoisomerasae IV, preventing the separation of daughter strands, fracturing DNA
    Explanation
    Fluoroquinolones function by inhibiting DNA Gyrase, which leads to the fracturing of DNA and ultimately bacterial cell death. They primarily target Gram-negative bacteria. Additionally, they target Gram-positive bacteria by inhibiting Topoisomerase IV, which prevents the separation of daughter strands and causes DNA fracturing. This mechanism of action specifically targets bacterial DNA and disrupts its synthesis, ultimately leading to the death of the bacteria.

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  • 37. 

    What causes Scalded Skin Syndrome?

    • A.

      Streptococcus pyogenes

    • B.

      Staphylococcus aureus

    • C.

      Clostridium tetani

    • D.

      E. Coli

    Correct Answer
    B. Staphylococcus aureus
    Explanation
    Scalded Skin Syndrome is caused by Staphylococcus aureus, a type of bacteria. This bacteria produces toxins that lead to the breakdown of the skin's outer layer, resulting in the characteristic symptoms of the syndrome. Staphylococcus aureus is commonly found on the skin and can enter the body through cuts, burns, or other openings in the skin. It is important to promptly treat and manage Scalded Skin Syndrome to prevent further complications and spread of the infection.

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  • 38. 

    What bacteria causes Scarlet Fever?

    • A.

      Staph aureus

    • B.

      Streptococcus pyogenes

    • C.

      Clostridium tetani

    • D.

      Corynebacterium diptheriae

    Correct Answer
    B. Streptococcus pyogenes
    Explanation
    Streptococcus pyogenes is the correct answer because it is the bacteria responsible for causing Scarlet Fever. Scarlet Fever is a bacterial infection that is characterized by a red rash, high fever, sore throat, and strawberry tongue. Streptococcus pyogenes, also known as Group A Streptococcus, is a common bacterium that can cause various infections, including strep throat, impetigo, and cellulitis. It produces toxins that cause the characteristic symptoms of Scarlet Fever. Staph aureus, Clostridium tetani, and Corynebacterium diptheriae are not associated with Scarlet Fever.

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  • 39. 

    What bacteria causes Diptheria?

    • A.

      Corynebacterium diptheriae

    • B.

      Clostridium botulinum

    • C.

      E. Coli

    • D.

      Streptococcus pyogenes

    Correct Answer
    A. Corynebacterium diptheriae
    Explanation
    Corynebacterium diphtheriae is the bacteria that causes Diptheria. This bacterium produces a toxin that can cause a thick, gray coating to form in the throat and can lead to difficulty breathing, heart problems, and even death if left untreated.

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  • 40. 

    What bacteria causes Toxic Shock Syndrome?

    • A.

      Strep pyogenes

    • B.

      Clostridium tetani

    • C.

      E. Coli

    • D.

      Staph aureus

    Correct Answer
    D. Staph aureus
    Explanation
    Staph aureus is the bacteria that causes Toxic Shock Syndrome. This bacterium produces toxins that can lead to the symptoms of the syndrome, including high fever, rash, low blood pressure, and organ failure. Staph aureus is commonly found on the skin and in the nose, and can enter the body through cuts, surgical wounds, or tampon use. It is important to note that while Strep pyogenes can cause other types of infections, it is not the bacteria responsible for Toxic Shock Syndrome.

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  • 41. 

    Toxins with adenylate cyclase activity have an immediate effect on host cells that promote bacterial invasion by causing increased levels of cyclic AMP and disruption of cell permeability.

    • A.

      True

    • B.

      False

    Correct Answer
    A. True
    Explanation
    Toxins with adenylate cyclase activity can have an immediate effect on host cells by increasing the levels of cyclic AMP and disrupting cell permeability. This can promote bacterial invasion by weakening the host cell's defenses and allowing the bacteria to enter and infect the cell more easily. Therefore, the statement that toxins with adenylate cyclase activity have an immediate effect on host cells that promote bacterial invasion is true.

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  • 42. 

    Which are obligate anaerobes?

    • A.

      Mycobacterium tuberculosis

    • B.

      Actinomyces

    • C.

      Bacteroides

    • D.

      Mycoplasma

    • E.

      Clostridium

    • F.

      Fusobacterium

    • G.

      Peptostreptococcus

    • H.

      Neisseria

    Correct Answer(s)
    B. Actinomyces
    C. Bacteroides
    E. Clostridium
    F. Fusobacterium
    G. Peptostreptococcus
    Explanation
    Actinomyces, Bacteroides, Clostridium, Fusobacterium, and Peptostreptococcus are obligate anaerobes. Obligate anaerobes are microorganisms that cannot survive in the presence of oxygen and can only grow in the absence of oxygen. These bacteria lack the enzymes necessary to detoxify reactive oxygen species, which are produced during aerobic respiration. Therefore, they rely on anaerobic respiration or fermentation for energy production.

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  • 43. 

    Where is Actinomyces found?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Colon

    • H.

      Distal urethra

    • I.

      Vagina

    Correct Answer(s)
    E. Oropharynx
    I. Vagina
    Explanation
    Actinomyces is a genus of bacteria that is commonly found in the oropharynx and vagina. These bacteria are part of the normal flora in these areas and do not usually cause any harm. However, under certain conditions, Actinomyces can cause infections, particularly in the oropharynx where it can lead to a condition called actinomycosis. Therefore, it is important to be aware of the presence of Actinomyces in these locations.

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  • 44. 

    Where is Bacteroides found?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Colon

    • H.

      Distal urethra

    • I.

      Vagina

    Correct Answer(s)
    E. Oropharynx
    F. Small intestine
    G. Colon
    H. Distal urethra
    I. Vagina
    Explanation
    Distal urethra

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  • 45. 

    Where is Clostridium found?

    • A.

      Skin

    • B.

      Conjunctiva

    • C.

      Ear

    • D.

      Nasopharynx

    • E.

      Oropharynx

    • F.

      Small intestine

    • G.

      Large intestine

    • H.

      Distal urethra

    • I.

      Vagina

    Correct Answer(s)
    F. Small intestine
    G. Large intestine
    I. Vagina
    Explanation
    Clostridium is a type of bacteria that can be found in various parts of the body. It is commonly found in the small intestine, large intestine, and vagina. In the small intestine, Clostridium can cause infections such as food poisoning. In the large intestine, it is a normal part of the gut flora but can sometimes cause infections such as Clostridium difficile colitis. In the vagina, Clostridium can be present as a part of the normal vaginal flora but can also cause infections such as bacterial vaginosis.

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Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 22, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Apr 18, 2016
    Quiz Created by
    Ebmpruett
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