Exam 4: Practice Questions

Penicillin and streptomycin are commonly used in syngerism because they display the same mode of action. True False

False

Ultraviolet light (UV) causes irreversible breaks in DNA strands. True False

False

Undergrowth of fungi after antibiotic use is commonly referred to as a superinfection. True False

False

A disk-diffusion test using Staphylococcus gave the following results: Disinfectant Zone of inhibition (mm) A 0 B 2.5 C 10 D 5 In the table, which compound was the most effective against Staphylococcus? A B C D The answer cannot be determined.

C

PABA serves as the competitive inhibitor in the action of sulfanilamides. True False

False

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 A 3 mm B 7 mm C 0 mm D 10 mm In the table, the antibiotic that exhibited bactericidal action was A. B. C. D. E. The answer cannot be determined based on the information provided.

E. The answer cannot be determined based on the information provided.

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 A 3 mm B 7 mm C 0 mm D 10 mm In the table, which antibiotic would be most useful for treating a Salmonella infection? A B C D E. The answer cannot be determined based on the information provided.

E. The answer cannot be determined based on the information provided.

Microorganisms placed in high concentrations of salts and sugars undergo lysis. True False

False

An antibiotic that attacks the LPS layer would be expected to have a narrow spectrum of activity. True False

True

Antiviral drugs target viral processes that occur during viral infection. True False

True

Autoclaving is the most effective method of moist heat sterilization. True False

True

Both trimethoprim and sulfamethoxazole inhibit reactions along the same metabolic pathway. True False

True

Due to its target, rifamycins can be effective over a broad spectrum. True False

True

Moist heat destroys organisms by denaturing proteins. True False

True

Pseudomonas has been found growing in quaternary ammonium compounds (quats). True False

True

The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature. True False

True

Which of the following organisms would MOST likely be sensitive to natural penicillin? a) Streptococcus pyogenes b) penicillinase-producing Neisseria gonorrhoeae c) Mycoplasma d) helminths e) Penicillium

a) Streptococcus pyogenes

Which of the following antibiotics causes misreading of mRNA? a) aminoglycoside - changes shape of 30S units b) oxazolidinone - prevents formation of 70S ribosome c) streptogamin - prevents release of peptide from 70S ribosome d) tetracyclines - bind with 30S subunit e) chloramphenicol - inhibits peptide bonds at 50S subunit

a) aminoglycoside - changes shape of 30S units

Mebendazole is used to treat cestode infections. It interferes with microtubule formation; therefore, it would NOT affect a) bacteria. b) helminths. c) fungi. d) human cells. e) protozoa.

a) bacteria

An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n) a) disinfectant. b) fungicide. c) aseptic. d) virucide. e) antiseptic.

a) disinfectant

Oxidizing agents include all of the following EXCEPT a) glutaraldehyde. b) ozone. c) hydrogen peroxide. d) chlorine. e) iodine.

a) glutaraldehyde.

In the presence of penicillin, a cell dies because a) it undergoes lysis. b) it lacks a cell wall. c) it lacks a cell membrane. d) its contents leak out. e) it plasmolyzes.

a) it undergoes lysis.

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 have ribosomes. d) they have more genes than bacteria. e) they do not reproduce.

a) their cells are structurally and functionally similar to human cells.

Which graph in the figure best depicts the effect of placing the culture in an autoclave for 15 minutes at time x? a b c d e

b

Which of the following antibiotics are used to treat fungal infections? 1. aminoglycosides 2. cephalosporins 3. griseofulvin 4. polyenes 5. bacitracin a) 1, 2, and 3 b) 3 and 4 c) 3, 4, and 5 d) 4 and 5 e) all of these antibiotics are used to treat fungal infections

b) 3 and 4

Which of the following antimicrobial agents is recommended for use against fungal infections? a) penicillin b) amphotericin B c) cephalosporin d) polymyxin e) bacitracin

b) amphotericin B

All of the following are effective for destroying prions EXCEPT a) incineration. b) boiling. c) proteases. d) NaOH + autoclaving at 134°C. e) Each of the answers will destroy prions.

b) boiling

Which of the following chemical agents is used for sterilization? a) alcohol b) ethylene oxide c) soap d) chlorine e) phenolics

b) ethylene oxide

A drug that inhibits mitosis, such as griseofulvin, would be more effective against a) wall-less bacteria. b) fungi. c) gram-negative bacteria. d) gram-positive bacteria. e) mycobacteria.

b) fungi

Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper? a) sunlight b) gamma radiation c) autoclave d) ultraviolet radiation e) microwaves

b) gamma radiation

The antibiotic tetracycline binds to the 30S subunit of the ribosome, as shown in the figure. The effect is to a) prevent transcription. b) interfere with the attachment of the tRNA to mRNA-ribosome complex. c) stop the ribosome from moving along the mRNA. d) prevent attachment of DNA. e) prevent peptide bond formation.

b) interfere with the attachment of the tRNA to mRNA-ribosome complex.

A drug binds to the ribosome as shown in the figure. The effect is to a) prevent the polypeptide from exiting the ribosome b) prevent peptide bond formation c) prevent mRNA-ribosome binding d) prevent ribosome formation e) prevent transcription

b) prevent peptide bond formation

The fate of E. coli O157:H7 in apple cider held at 8°C for 2 weeks, with and without preservatives, is shown below: Bacteria/ml Cider only 2.2 Cider with potassium sorbate 2.0 Sodium benzoate 0 Potassium sorbate + sodium benzoate 0 In the table, which preservative is most effective? a) potassium sorbate b) sodium benzoate c) potassium sorbate + sodium benzoate d) no preservative

b) sodium benzoate

In the figure, what is the thermal death time? a) The answer cannot be determined. b) 100°C c) 60 minutes d) 120 minutes e) 150°C

c) 60 minutes

Which of the following statements is FALSE? a) Fluoroquinolone inhibits DNA synthesis. b) Azoles inhibit plasma membrane synthesis. c) Interferon inhibits glycolysis. d) Acyclovir inhibits DNA synthesis. e) Amantadine inhibits the release of viral nucleic acid.

c) Interferon inhibits glycolysis.

Most of the available antimicrobial agents are effective against a) protozoa. b) fungi. c) bacteria. d) viruses. e) All of the answers are correct.

c) bacteria

All of the following substances are used to preserve foods EXCEPT a) sodium nitrite. b) calcium propionate. c) biguanides. d) potassium sorbate. e) nisin.

c) biguanides

Niclosamide prevents ATP generation in mitochondria. You would expect this drug to be effective against a) viruses. b) Mycobacterium tuberculosis. c) helminths. d) gram-positive bacteria. e) gram-negative bacteria.

c) helminths

All of the following are methods of food preservation EXCEPT a) high pressure. b) osmotic pressure. c) microwaves. d) ionizing radiation. e) desiccation.

c) microwaves

Which graph in the figure best depicts the effect of placing the culture at 7°C at time x? a b c d e

d

Which of the following is a limitation of the autoclave? a) It requires an excessively long time to achieve sterilization. b) It cannot inactivate viruses. c) It cannot kill endospores. d) It cannot be used with heat-labile materials. e) It cannot be used with glassware.

d) It cannot be used with heat-labile materials.

Which of the following statements about drugs that competitively inhibit DNA polymerase or RNA polymerase is FALSE? a) They are used against viral infections. b) They interfere with protein synthesis. c) They cause mutations. d) They cause cellular plasmolysis. e) They can affect host cell DNA.

d) They cause cellular plasmolysis.

Which of the following substances is used for surgical hand scrubs? a) glutaraldehyde b) chlorine bleach c) phenol d) chlorhexidine e) soap

d) chlorhexidine

Which of the following is the best method to sterilize heat-labile solutions? a) dry heat b) freezing c) autoclave d) membrane filtration e) pasteurization

d) membrane filtration

Which of the following does NOT achieve sterilization? a) ethylene oxide b) autoclave c) supercritical fluids d) pasteurization e) dry heat

d) pasteurization

All of the following factors contribute to hospital-acquired infections EXCEPT a) some bacteria metabolize disinfectants. b) invasive procedures can provide a portal of entry for bacteria. c) gram-negative bacteria are often resistant to disinfectants. d) bacteria may be present in commercial products such as mouthwash. e) All of these factors may contribute to hospital-acquired infection.

e) All of these factors may contribute to hospital-acquired infection.

Which of the following statements about drug resistance is FALSE? a) It may be transferred from one bacterium to another during conjugation. b) It may be due to enzymes that degrade some antibiotics. c) It may be carried on a plasmid. d) It may be due to increased uptake of a drug. e) It is found only in gram-negative bacteria.

e) It is found only in gram-negative bacteria.

Which of the following disinfectants acts by disrupting the plasma membrane? a) halogens b) soaps c) aldehydes d) heavy metals e) bisphenols

e) bisphenols

The structures of the influenza drug Tamiflu and sialic acid, the substrate for influenza viruss neuramidase, are shown in the figure. What is the method of action of Tamiflu? a) inhibits cell wall synthesis b) prevents synthesis of virus spikes c) inhibits synthesis of neuramidase d) inhibits plasma membrane synthesis e) competitive inhibition

e) competitive inhibition

Which method below is used to preserve food by slowing the metabolic processes of foodborne microbes? a) nonionizing radiation b) pasteurization c) ionizing radiation d) lyophilization e) freezing

e) freezing

Which of the following results in lethal damage to nucleic acids? a) heat b) radiation c) certain chemicals d) heat and radiation e) heat, radiation, and some chemicals

e) heat, radiation, and some chemicals

Which of the following methods of action would be bacteriostatic? a) competitive inhibition with folic acid synthesis b) inhibition of cell wall synthesis c) competitive inhibition with DNA gyrase d) injury to plasma membrane e) inhibition of protein synthesis

e) inhibition of protein synthesis

Which of the following antibiotics does NOT interfere with cell wall synthesis? a) vancomycin b) natural penicillins c) cephalosporins d) semisynthetic penicillins e) macrolides

e) macrolides

The antimicrobial drugs with the broadest spectrum of activity are a) penicillin G. b) chloramphenicol. c) aminoglycosides. d) macrolides. e) tetracyclines.

e) tetracyclines.

Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization. True False

false

Desiccation is a reliable form of sterilization. True False

false

Some antimicrobial chemicals are considered to be disinfectants and antiseptics. True False

true