Question 1

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

Accepted Answer

Sterilization removes all living microbes, while disinfection only kills pathogenic microbes.

Question 2

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

Accepted Answer

Ethylene oxide gas sterilization

Question 3

Which of the following is the principle of selective toxicity in antimicrobial therapy?

Accepted Answer

The drug targets only the pathogen without harming the host.

Question 4

Which enzyme protects aerobic bacteria from the effects of superoxide radicals ($$O_2$$^-$$)?

Accepted Answer

Superoxide dismutase (SOD)

Question 5

A bacterium grows optimally at $$37^{\circ}C$ and is killed at 63$$^{\circ}$$C$$ after 30 minutes. What is its classification?

Accepted Answer

Mesophile

Question 6

Which physical method of microbial control is most effective for sterilizing air in surgical units?

Accepted Answer

HEPA filtration

Question 7

What is the mechanism by which halogens such as chlorine and iodine control microbial growth?

Accepted Answer

Oxidation of proteins, inactivating enzymes

Question 8

Which of the following would NOT be effectively controlled by pickling (using salt and vinegar)?

Accepted Answer

Extreme halophiles

Question 9

Which antimicrobial agent acts by inhibiting cell wall synthesis through preventing cross-linkage of NAM subunits?

Accepted Answer

Penicillin

Question 10

A bacterial cell placed in a hypertonic solution will most likely undergo which process?

Accepted Answer

Plasmolysis

Question 11

Which of the following is a limitation of autoclave sterilization?

Accepted Answer

Oily substances are not effectively sterilized

Question 12

Which type of bacteria would grow only at the top of a test tube of liquid medium?

Accepted Answer

Obligate aerobe

Question 13

Which chemical agent is used as a sterilant at 20% concentration and acts by cross-linking proteins and nucleic acids?

Accepted Answer

Formaldehyde

Question 14

Which antimicrobial drug acts by competitive inhibition of folic acid synthesis, a process not found in humans?

Accepted Answer

Sulfonamides

Question 15

Which of the following is NOT a mechanism of antibiotic resistance?

Accepted Answer

Increasing the permeability of the cell membrane to the drug

Question 16

Which of the following statements about pasteurization is correct?

Accepted Answer

Flash pasteurization at $$71.6^{\circ}C$ for 15 seconds kills pathogens but does not sterilize

Question 17

Which of the following would be most susceptible to microbial control methods?

Accepted Answer

Enveloped viruses

Question 18

Which physical method of microbial control is most appropriate for sterilizing heat-sensitive liquids such as blood solutions?

Accepted Answer

Membrane filtration

Question 19

Which of the following best explains why hand sanitizers should contain at least 60% ethanol?

Accepted Answer

Lower concentrations are less effective at denaturing proteins and disrupting membranes

Question 20

Which of the following is a real-world example of selective toxicity in antimicrobial therapy?

Accepted Answer

Penicillin targets bacterial cell wall synthesis, which is absent in human cells

Microbial Control: Physical and Chemical Methods, and Factors Affecting Microbial Growth

Study Guide - Practice Questions