Question 1

Which of the following best describes the process of sterilization?

Accepted Answer

Complete destruction or removal of all viable organisms, including living cells, spores, viruses, and viroids

Question 2

A hospital needs to sterilize heat-resistant glassware. Which physical method is most appropriate?

Accepted Answer

Autoclaving at $$121\ ^\circ \mathrm{C}$$ for 15 minutes under pressure

Question 3

Which of the following statements about microbial death is correct?

Accepted Answer

Microbial death follows an exponential pattern, with cells dying at a constant rate

Question 4

Which factor does NOT directly influence the effectiveness of an antimicrobial agent?

Accepted Answer

Color of the microorganism

Question 5

A disinfectant is used to clean a laboratory bench. Which property is most important for its effectiveness?

Accepted Answer

Activity in the presence of organic matter

Question 6

Which chemical agent is most suitable for disinfecting drinking water and is effective against Giardia?

Accepted Answer

Chlorine

Question 7

Why is autoclaving more effective than boiling for sterilization?

Accepted Answer

Autoclaving uses saturated steam under pressure, reaching higher temperatures and killing endospores

Question 8

Which of the following is a limitation of using UV radiation for microbial control?

Accepted Answer

It has low penetrating ability and is mainly used for surface decontamination

Question 9

A pharmaceutical company needs to sterilize heat-sensitive antibiotics. Which method should they use?

Accepted Answer

Ionizing radiation (gamma rays)

Question 10

Which equation best represents the exponential death of microorganisms during heat treatment?

Accepted Answer

$$N_t = N_0$ e$$^{-kt}$$

Question 11

Which chemical agent is used as a general antiseptic for newborns' eyes to prevent gonococcal infections?

Accepted Answer

Silver nitrate ($$\mathrm{AgNO}_3)$$

Question 12

Which method is most effective for reducing microbial populations in air in hospital theatres?

Accepted Answer

HEPA filtration

Question 13

Which group of chemical agents acts by denaturing proteins and disrupting cell membranes, and is tuberculocidal?

Accepted Answer

Phenolics

Question 14

Which of the following is NOT a characteristic of an ideal chemical agent for microbial control?

Accepted Answer

High cost and limited availability

Question 15

Which method is used to test the effectiveness of autoclaving for sterilization?

Accepted Answer

Using endospores of Bacillus stearothermophilus or Clostridium

Question 16

Which of the following is true about quaternary ammonium compounds?

Accepted Answer

They are safe, easy to use, but inactivated by hard water and soap

Question 17

Which physical method is most suitable for sterilizing heat-sensitive solutions such as antibiotics?

Accepted Answer

Filtration

Question 18

Which of the following best describes the action of aldehydes as chemical agents?

Accepted Answer

They bind and inactivate DNA and proteins by reacting with –NH2, –SH, and –COOH groups

Question 19

Which of the following is a limitation of dry heat sterilization?

Accepted Answer

It is not suitable for heat-labile substances such as plastics and rubber items

Question 20

Which of the following is the minimum inhibitory concentration (MIC)?

Accepted Answer

The smallest amount of agent needed to inhibit the growth of a test organism

Control of Microorganisms by Physical and Chemical Agents

Study Guide - Practice Questions