Question 1

Which of the following best describes the process of sterilization?

Accepted Answer

The removal of all living microorganisms, including endospores, from an object or environment.

Question 2

What is the main difference between sterilization and commercial sterilization?

Accepted Answer

Sterilization destroys all forms of microbial life, while commercial sterilization only destroys Clostridium botulinum endospores.

Question 3

Clostridium botulinum can cause botulism by which mechanism?

Accepted Answer

Producing a neurotoxin after endospores germinate in anaerobic environments.

Question 4

Which suffix indicates an agent that kills bacteria?

Accepted Answer

-cidal

Question 5

Which of the following can be safely applied to living tissue to reduce microbial load?

Accepted Answer

Antiseptics such as alcohol or iodine.

Question 6

What is the main difference between degerming and sanitization?

Accepted Answer

Degerming is the mechanical removal of microbes from a limited area, while sanitization reduces microbial counts to safe levels on objects.

Question 7

Refer to the first image (logarithmic death curve). If the DRT (decimal reduction time) is 1 minute, how many viable cells remain after 3 minutes if you start with $$10^6$$ cells?

Accepted Answer

$$10^3$$

Question 8

Which of the following factors does NOT directly affect the rate of microbial death during sterilization?

Accepted Answer

Color of the microbial cells.

Question 9

Which method would you use to sterilize a heat-sensitive culture medium containing proteins and sugars?

Accepted Answer

Filtration

Question 10

Which of the following statements about pasteurization is correct?

Accepted Answer

Pasteurization does not necessarily achieve sterilization.

Question 11

Which of the following is the most effective concentration of ethanol for killing microorganisms?

Accepted Answer

70%

Question 12

Which physical method kills microorganisms by oxidation of cellular components?

Accepted Answer

Dry heat sterilization

Question 13

Which of the following statements about cold temperatures is correct?

Accepted Answer

Cold temperatures are primarily bacteriostatic.

Question 14

Which type of radiation is most effective for sterilizing plastic medical equipment?

Accepted Answer

Ionizing radiation (e.g., gamma rays)

Question 15

Which chemical agent should NOT be used on living tissue due to its toxicity?

Accepted Answer

Bleach

Question 16

Refer to the second image (disk diffusion test). Which chemical would be most effective for cleaning a spill of Bacteria A based on the size of the zone of inhibition?

Accepted Answer

Chlorine

Question 17

How do phenol and phenolics kill microorganisms?

Accepted Answer

By disrupting plasma membranes and denaturing proteins.

Question 18

Why is hydrogen peroxide not recommended for use on open wounds?

Accepted Answer

Catalase in tissues breaks it down, reducing its effectiveness.

Question 19

Refer to the third image (effectiveness of antiseptics). If you spill Bacillus anthracis on your hand and have access to 1% iodine in 70% ethanol and Zephiran, which should you use?

Accepted Answer

1% iodine in 70% ethanol

Question 20

Which of the following best describes the effect of a bacteriostatic agent?

Accepted Answer

It inhibits the growth and reproduction of bacteria without killing them.

Microbiology Exam Study Guide: Control of Microbial Growth

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