Enveloped viruses < Naked viruses < Endospores

Used in direct contact with blood or tissues

They can filter all organisms that pass through and have no pores

Question 1

Which of the following best defines 'sterilize' in the context of microbiology?

Accepted Answer

All microorganisms dead

Question 2

Why are naked viruses generally harder to kill than enveloped viruses?

Accepted Answer

They have a protein coat that is less sensitive to environmental changes

Question 3

Which of the following structures is the primary target for chemical disinfectants in bacteria?

Accepted Answer

Cytoplasmic membrane

Question 4

A hospital is preparing surgical instruments for use in an operation. Which level of decontamination is required?

Accepted Answer

Sterilization

Question 5

Which of the following statements about membrane filtration is correct?

Accepted Answer

It can only filter organisms larger than its $0.2\ \mu m$ pore size

Question 6

Which method of pasteurization is most effective for preserving flavor and nutrients in milk while reducing microbial load?

Accepted Answer

Batch pasteurization ($63^\circ C$ for 30 min)

Question 7

Which of the following is NOT typically killed by high-level disinfectants?

Accepted Answer

Endospores

Question 8

A laboratory technician needs to disinfect a surface contaminated with Mycobacterium tuberculosis. Which level of disinfection is required?

Accepted Answer

Intermediate-level disinfection

Question 9

Which of the following best describes the effect of water activity ($a_w$) on microbial growth?

Accepted Answer

Most bacteria need high $a_w$ to grow, while fungi can survive with low $a_w$

Question 10

Which of the following is a correct match between the decontamination method and its definition?

Accepted Answer

Disinfect: Use on inanimate surfaces

Question 11

A food processing plant wants to reduce the growth rate of spoilage organisms in canned food for long-term storage. Which process should they use?

Accepted Answer

Preservation

Question 12

Which of the following is a reason why moist heat is more effective than dry heat for decontamination?

Accepted Answer

Moist heat has a higher heat capacity, allowing better penetration

Question 13

Which of the following is the correct order of resistance to decontamination, from least to most resistant?

Accepted Answer

Enveloped viruses < Naked viruses < Endospores

Question 14

A filter with a pore size of $0.2\ \mu m$ is used to sterilize a solution. Which of the following will NOT be removed by this filter?

Accepted Answer

Viruses

Question 15

Which of the following best describes a 'critical' medical instrument?

Accepted Answer

Used in direct contact with blood or tissues

Question 16

Which of the following is a target for chemical disinfectants in bacteria?

Accepted Answer

Proteins

Question 17

Which of the following is true regarding the use of depth (HEPA) filters?

Accepted Answer

They can filter all organisms that pass through and have no pores

Question 18

Which of the following is the main reason why endospores are difficult to kill?

Accepted Answer

They have a thick protein coat and are metabolically inactive

Question 19

Which of the following is the best method to ensure the destruction of all microbial life, including endospores, on surgical instruments?

Accepted Answer

Sterilization using autoclaving

Question 20

A nurse is cleaning a stethoscope that only comes into contact with intact skin. Which level of decontamination is appropriate?

Accepted Answer

Low-level disinfection

Microbial Decontamination and Disinfection: Key Concepts and Methods

Study Guide - Practice Questions