Question 1

Which term best describes the removal or destruction of all living microbes, including spores and viruses, from an object?

Accepted Answer

Sterilization

Question 2

A hospital uses a chemical agent to reduce the number of pathogens on surgical instruments. What is the most accurate term for this process?

Accepted Answer

Disinfection

Question 3

Why does microbial death due to antimicrobial treatment occur at a logarithmic rate rather than all at once?

Accepted Answer

Damage accumulates at different rates in individual cells

Question 4

If a disinfectant kills 99.9% of a population of $$1,000,000$$ bacterial cells, how many viable cells remain?

Accepted Answer

$$1,000$$

Question 5

Which physical method is most appropriate for sterilizing heat-sensitive medical plastics?

Accepted Answer

Ethylene oxide gas

Question 6

A bacteriostatic agent is added to a bacterial culture. What is the expected effect?

Accepted Answer

Cell growth is inhibited, but cells are not killed

Question 7

Which factor does NOT influence the efficacy of an antimicrobial treatment?

Accepted Answer

Color of the disinfectant

Question 8

What is the D-value in microbial control?

Accepted Answer

The time required to kill 90% of a microbial population at a specific condition

Question 9

Which chemical agent acts by disrupting lipids in the plasma membrane and denaturing proteins, and remains active on surfaces after application?

Accepted Answer

Phenolics

Question 10

A food company wants to reduce microbial numbers in juice without altering its flavor. Which method is most suitable?

Accepted Answer

Pasteurization at $$72^	ext{\circ}C $$for 15 seconds

Question 11

Which of the following is the correct order of increasing resistance to chemical biocides?

Accepted Answer

Viruses \u003c Fungi \u003c Bacterial spores

Question 12

A laboratory technician uses membrane filtration with a pore size of $$0.2\ \mu m to $$sterilize a solution. What type of microbes will be removed?

Accepted Answer

All bacteria and larger microbes

Question 13

Which chemical method is most effective for surface disinfection but does NOT penetrate well and mainly causes mutations by fragmenting nucleic acids?

Accepted Answer

Non-ionizing radiation (UV)

Question 14

A disinfectant is used at a lower concentration than recommended. What is a likely consequence?

Accepted Answer

Microbes may develop resistance more easily

Question 15

Which of the following best describes the action of quaternary ammonium compounds?

Accepted Answer

Disrupt plasma membranes and denature proteins

Question 16

A patient’s wound is treated with an agent that reduces pathogens on living tissue. What is this process called?

Accepted Answer

Antisepsis

Question 17

Which of the following is a multi-step problem: If a bacterial culture starts with $$10^6$$ cells and is treated with an agent with a D-value of 2 minutes, how many cells remain after 6 minutes?

Accepted Answer

$$10^3$$ cells

Question 18

Which chemical agent is used as a gaseous sterilant for heat-sensitive materials and acts by denaturing and modifying proteins?

Accepted Answer

Ethylene oxide

Question 19

Which of the following is a correct application of the disk diffusion method?

Accepted Answer

Measuring the zone of inhibition to assess disinfectant efficacy

Question 20

Which physical method is most suitable for preserving microbial cultures for long-term storage?

Accepted Answer

Refrigeration or freezing at $$-20^	ext{\circ}C or$$ $$-80^	ext{\circ}C$$

Control of Microbial Growth: Principles, Methods, and Efficacy

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