Question 1

Which of the following best describes the process of sterilization?

Accepted Answer

The complete removal or destruction of all microorganisms, including bacterial endospores, used on inanimate objects.

Question 2

A hospital needs to sterilize heat-sensitive medical equipment. Which method is most appropriate?

Accepted Answer

Cold sterilization using ethylene oxide gas

Question 3

Which statement correctly compares moist heat and dry heat sterilization?

Accepted Answer

Moist heat sterilizes in shorter times and at lower temperatures than dry heat.

Question 4

A laboratory technician uses an autoclave set at $121^	ext{o}C$ and 15 psi for 15 minutes. What is the primary purpose of this procedure?

Accepted Answer

Sterilization of media and instruments

Question 5

Which of the following is a limitation of ultraviolet (UV) radiation as a microbial control method?

Accepted Answer

Its poor penetration through solids limits its applications to surface disinfection.

Question 6

Which antimicrobial drug class works by inhibiting the synthesis of folic acid in bacteria?

Accepted Answer

Sulfonamides

Question 7

A patient is diagnosed with a Gram-negative bacterial infection. Which antibiotic is most likely to be effective?

Accepted Answer

Polymyxin

Question 8

Which of the following best explains the concept of selective toxicity in antimicrobial therapy?

Accepted Answer

Drugs kill or inhibit microbial cells without simultaneously damaging host tissues.

Question 9

Which mechanism is responsible for the development of drug resistance in bacteria?

Accepted Answer

Acquisition of new genes via horizontal gene transfer

Question 10

A physician prescribes antibiotics for a viral infection. What is a potential consequence of this practice?

Accepted Answer

Development of antibiotic resistance in bacteria

Question 11

Which of the following drugs acts by binding to the 30S ribosomal subunit and causing misreading of mRNA?

Accepted Answer

Streptomycin

Question 12

Why are beta-lactam antibiotics, such as penicillins and cephalosporins, generally more effective against Gram-positive bacteria?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer that is easily targeted by these drugs.

Question 13

A food processing plant wants to reduce microbial contamination on packaged lettuce. Which physical method is most suitable?

Accepted Answer

Ionizing radiation (gamma rays)

Question 14

Which test is used to determine the minimum inhibitory concentration (MIC) of an antibiotic?

Accepted Answer

Dilution test

Question 15

A patient with HIV is prescribed a drug that acts as a nucleoside reverse transcriptase inhibitor (NRTI). What is the mechanism of action?

Accepted Answer

Competitive inhibition by inserting into HIV DNA and terminating synthesis

Question 16

Which of the following is a reason why farmers' use of antibiotics in animal feed contributes to antibiotic resistance?

Accepted Answer

It promotes the selection of resistant bacteria in livestock.

Question 17

Which chemical agent is suitable for sterilizing reusable medical equipment that cannot withstand high temperatures?

Accepted Answer

Bleach (liquid sterilant)

Question 18

A microbiologist observes a clear zone around an antibiotic disk on an agar plate. What does this zone represent?

Accepted Answer

Zone of inhibition where bacteria are killed or growth is prevented

Question 19

Which of the following is a broad-spectrum antibiotic effective against both Gram-positive and Gram-negative bacteria?

Accepted Answer

Tetracycline

Question 20

Which of the following best describes the action of interferons (IFN) in viral infections?

Accepted Answer

They are glycoproteins that reduce healing time and complications, and slow the progress of certain viral diseases.

Physical and Chemical Agents for Microbial Control

Study Guide - Practice Questions