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Protozoan and helminthic diseases are difficult to treat because


A) their cells are structurally and functionally similar to human cells.
B) they replicate inside human cells.
C) they do not reproduce.
D) they have more genes than bacteria.
E) they do not have ribosomes.

F) A) and D)
G) A) and C)

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Penicillin was considered a ʺmiracle drugʺ for all of the following reasons EXCEPT


A) it was the first antibiotic.
B) it has selective toxicity.
C) it does not affect eukaryotic cells.
D) it kills bacteria.
E) it inhibits gram-positive cell wall synthesis.

F) B) and E)
G) A) and B)

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Use of antibiotics in animal feed leads to antibiotic-resistant bacteria because


A) the antibiotics kill susceptible bacteria, but the few that are naturally resistant live and reproduce, and their progeny repopulate the host animal.
B) bacteria from other animals replace those killed by the antibiotics.
C) the antibiotics persist in soil and water.
D) the antibiotics cause new mutations to occur in the surviving bacteria, which results in resistance to antibiotics.
E) the few surviving bacteria that are affected by the antibiotics develop immunity to the antibiotics, which they pass on to their progeny.

F) B) and D)
G) None of the above

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Which of the following would be selective against the tubercle bacillus?


A) streptogramin  inhibits protein synthesis
B) ethambutol  inhibits mycolic acid synthesis
C) vancomycin  inhibits peptidoglycan synthesis
D) bacitracin  inhibits peptidoglycan synthesis
E) streptomycin  inhibits protein synthesis

F) C) and D)
G) B) and C)

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Figure 20.1 Figure 20.1   The antibiotic tetracycline binds to the 30S subunit of the ribosome, as shown by the dark black bar on the right portion of the diagram in Figure 20.1. The effect is to A)  prevent peptide bond formation. B)  stop the ribosome from moving along the mRNA. C)  prevent transcription. D)  interfere with the attachment of the tRNA to mRNA-ribosome complex. E)  prevent attachment of DNA. The antibiotic tetracycline binds to the 30S subunit of the ribosome, as shown by the dark black bar on the right portion of the diagram in Figure 20.1. The effect is to


A) prevent peptide bond formation.
B) stop the ribosome from moving along the mRNA.
C) prevent transcription.
D) interfere with the attachment of the tRNA to mRNA-ribosome complex.
E) prevent attachment of DNA.

F) None of the above
G) A) and E)

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Which of the following antibiotics is NOT bactericidal?


A) polyenes
B) cephalosporins
C) penicillin
D) aminoglycosides
E) rifampins

F) C) and D)
G) B) and C)

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Table 20.2 The following results were obtained from a disk-diffusion test for microbial susceptibility to antibiotics. Staphylococcus aureus was the test organism.  Antibiotic  Zone of Inhibition A3 mmB7 mmC0 mmD10 mm\begin{array} { | l | l | } \hline { \text { Antibiotic } } & \text { Zone of Inhibition } \\\hline \mathrm { A } & 3 \mathrm {~mm} \\\hline \mathrm { B } & 7 \mathrm {~mm} \\\hline \mathrm { C } & 0 \mathrm {~mm} \\\hline \mathrm { D } & 10 \mathrm {~mm} \\\hline\end{array} -In Table 20.2, the most effective antibiotic tested was


A) A.
B) B.
C) C.
D) D.
E) The answer cannot be determined based on the information provided.

F) A) and B)
G) B) and E)

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More than half of our antibiotics are


A) synthesized in laboratories.
B) produced by Fleming.
C) produced by eukaryotic organisms.
D) produced by fungi.
E) produced by bacteria.

F) A) and D)
G) B) and D)

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Can you determine both MIC and MBC from an E-test? Explain.

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Answered by ExamLex AI

No, the E-test is primarily used to dete...

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Which of the following antibiotics causes misreading of mRNA?


A) tetracyclines  bind with 30S subunit
B) aminoglycoside  changes shape of 30S units
C) chloramphenicol  inhibits peptide bonds at 50S subunit
D) oxazolidinone  prevents formation of 70S ribosome
E) streptogamin  prevents release of peptide from 70S ribosome

F) All of the above
G) A) and B)

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Only microbes produce antimicrobial peptides.

A) True
B) False

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Which one of the following does NOT belong with the others?


A) cephalosporin
B) monobactam
C) penicillin
D) bacitracin
E) streptomycin

F) D) and E)
G) C) and E)

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Table 20.2 The following results were obtained from a disk-diffusion test for microbial susceptibility to antibiotics. Staphylococcus aureus was the test organism.  Antibiotic  Zone of Inhibition A3 mmB7 mmC0 mmD10 mm\begin{array} { | l | l | } \hline { \text { Antibiotic } } & \text { Zone of Inhibition } \\\hline \mathrm { A } & 3 \mathrm {~mm} \\\hline \mathrm { B } & 7 \mathrm {~mm} \\\hline \mathrm { C } & 0 \mathrm {~mm} \\\hline \mathrm { D } & 10 \mathrm {~mm} \\\hline\end{array} -In Table 20.2, the antibiotic that exhibited bactericidal action was


A) A.
B) B.
C) C.
D) D.
E) The answer cannot be determined based on the information provided.

F) A) and B)
G) A) and C)

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Most of the available antimicrobial agents are effective against


A) bacteria.
B) viruses.
C) protozoa.
D) fungi.
E) All of the answers are correct.

F) B) and D)
G) None of the above

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Which of the following antimicrobial agents is recommended for use against fungal infections?


A) polymyxin
B) bacitracin
C) amphotericin B
D) cephalosporin
E) penicillin

F) A) and E)
G) A) and D)

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Which of the following methods of action would be bacteriostatic?


A) competitive inhibition with folic acid synthesis
B) competitive inhibition with DNA gyrase
C) injury to plasma membrane
D) inhibition of protein synthesis
E) inhibition of cell wall synthesis

F) B) and C)
G) A) and E)

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Phage therapy has been used in the past as an antiviral treatment.

A) True
B) False

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An official from an international health agency predicts that if all countries enacted legislation to only sell antibiotics with a prescription, then the rate of antibiotic resistant would ʺgrind to a halt.ʺ Do you agree? Explain.

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Which of the following does NOT affect eukaryotic cells?


A) antifungal drugs
B) semisynthetic penicillins
C) antiprotozoan drugs
D) antihelminthic drugs
E) nucleotide analogs

F) B) and D)
G) All of the above

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Which of the following organisms would MOST likely be sensitive to natural penicillin?


A) penicillinase-producing Neisseria gonorrhoeae
B) helminths
C) Penicillium
D) Mycoplasma
E) Streptococcus pyogenes

F) C) and D)
G) A) and B)

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