Autoclaving at $121^\\circ C$ and 15 psi

Question 1

Which of the following best describes the difference between sterilization and disinfection?

Accepted Answer

Sterilization destroys all microbial life, including endospores; disinfection destroys only vegetative pathogens.

Question 2

A hospital needs to sterilize heat-sensitive surgical instruments. Which method is most appropriate?

Accepted Answer

Filtration

Question 3

Which chemical agent is known for its broad spectrum, sporicidal activity, and is suitable for heat-sensitive tools?

Accepted Answer

Glutaraldehyde

Question 4

Why does the microbial death rate follow a logarithmic curve when exposed to a disinfectant?

Accepted Answer

A constant proportion of organisms die per unit time, not a constant number.

Question 5

Which of the following physical control methods is most effective at destroying endospores?

Accepted Answer

Autoclaving at $121^\circ C$ and 15 psi

Question 6

A patient is infected with Mycobacterium tuberculosis. Which antibiotic mechanism is most effective?

Accepted Answer

Inhibition of mycolic acid synthesis

Question 7

Which of the following is a mechanism by which bacteria develop resistance to antibiotics?

Accepted Answer

Enzymatic inactivation of the drug

Question 8

Which chemical class is most effective against enveloped viruses due to membrane disruption?

Accepted Answer

Quaternary ammonium compounds (QACs)

Question 9

A researcher uses the disk diffusion test to evaluate disinfectant effectiveness. What does a larger zone of inhibition indicate?

Accepted Answer

Greater effectiveness of the disinfectant

Question 10

Which of the following antibiotics targets the 30S ribosomal subunit?

Accepted Answer

Aminoglycosides

Question 11

A patient is exposed to a bacterial exotoxin. Which statement is most accurate?

Accepted Answer

Exotoxins are secreted proteins and are usually highly potent.

Question 12

Which portal of entry is most commonly used by respiratory pathogens?

Accepted Answer

Mucous membranes

Question 13

Which of the following is a virulence factor that helps bacteria evade phagocytosis?

Accepted Answer

Capsule

Question 14

Which of the following statements about selective toxicity is correct?

Accepted Answer

Selective toxicity is harder to achieve for viruses, fungi, protozoa, and helminths than for bacteria.

Question 15

A disinfectant is tested on a surface contaminated with organic matter. What is the expected effect?

Accepted Answer

Organic matter reduces the effectiveness of the disinfectant.

Question 16

Which of the following is the correct order of relative resistance to chemical agents (from most to least resistant)?

Accepted Answer

Endospores $>$ Mycobacteria $>$ Cysts $>$ Non-enveloped viruses $>$ Fungi $>$ Vegetative cells $>$ Enveloped viruses

Question 17

Which mechanism is responsible for the action of sulfonamides?

Accepted Answer

Inhibition of folate synthesis

Question 18

A patient receives penicillin for a bacterial infection. Which enzyme could confer resistance to this antibiotic?

Accepted Answer

Beta-lactamase

Question 19

Which of the following is a physical method that reduces pathogens but does NOT sterilize?

Accepted Answer

Pasteurization

Question 20

A food processing plant wants to reduce microbial contamination on surfaces. Which chemical agent is most appropriate for non-critical surfaces?

Accepted Answer

Quaternary ammonium compounds (QACs)

Control of Microbial Growth: Study Guide and Review

Study Guide - Practice Questions