Question 1

Which of the following best defines sterilization in the context of microbial control?

Accepted Answer

The complete removal or destruction of all viable microorganisms, including endospores.

Question 2

Which microbial form is considered the most resistant to physical and chemical control methods?

Accepted Answer

Prions

Question 3

A hospital technician needs to sterilize heat-sensitive liquid media. Which method is most appropriate?

Accepted Answer

Filtration through a membrane with small pore size

Question 4

Which of the following statements about microbicidal and microbistatic agents is correct?

Accepted Answer

Microbicidal agents result in microbial death, while microbistatic agents only inhibit growth.

Question 5

Which of the following is NOT a cellular target for physical and chemical antimicrobial agents?

Accepted Answer

Mitochondria

Question 6

A nurse prepares a patient’s skin with iodine before surgery. This process is best described as:

Accepted Answer

Antisepsis

Question 7

Which of the following best describes the action of moist heat on microbial cells?

Accepted Answer

Coagulation and denaturation of proteins

Question 8

Which physical method is most effective for sterilizing inoculating loops in a microbiology laboratory?

Accepted Answer

Incineration

Question 9

Which of the following statements about the use of UV radiation for microbial control is correct?

Accepted Answer

UV radiation is most lethal at wavelengths around 260 nm.

Question 10

A solution is prepared by dissolving 5 grams of a chemical in 95 mL of water. What is the percentage solution by weight/volume?

Accepted Answer

$$5\%$$

Question 11

Which of the following is a disadvantage of using phenolic compounds as disinfectants?

Accepted Answer

They are corrosive and can cause skin irritation.

Question 12

Which of the following is the correct definition of thermal death time (TDT)?

Accepted Answer

The shortest length of time required to kill all test microbes at a specified temperature.

Question 13

Which of the following is NOT a desirable quality in a germicide?

Accepted Answer

Corrosiveness to metals and skin

Question 14

Which of the following statements about the effects of cold on microorganisms is correct?

Accepted Answer

Cold treatment is microbistatic and slows microbial growth.

Question 15

Which of the following is a high-level germicide that can be used as a sterilant?

Accepted Answer

Hydrogen peroxide ($$H_2O_2)$$

Question 16

A laboratory technician needs to sterilize glassware contaminated with bacteria. Which method is most appropriate?

Accepted Answer

Hot air oven at 160°C for 2 hours

Question 17

Which of the following best explains why adding large amounts of salt or sugar preserves food?

Accepted Answer

It creates a hypertonic environment, causing plasmolysis in bacteria.

Question 18

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

Accepted Answer

It does not penetrate solids or opaque surfaces well.

Question 19

Which of the following is the correct order of microbial resistance to control agents, from least to most resistant?

Accepted Answer

Enveloped viruses, Gram-positive bacteria, Mycobacterium, Bacterial endospores, Prions

Question 20

Which of the following is a disadvantage of boiling as a method of microbial control?

Accepted Answer

It can easily recontaminate items after removal from water.

Physical and Chemical Control of Microbes

Study Guide - Practice Questions