Question 1

Which of the following best describes an epidemic disease?

Accepted Answer

A disease that affects many people in a given area in a short time, such as influenza outbreaks.

Question 2

Which of the following is an example of a nonliving reservoir of infection?

Accepted Answer

A contaminated water source harboring Vibrio cholerae.

Question 3

A hospital patient develops a urinary tract infection after catheterization. This infection is best classified as:

Accepted Answer

A nosocomial infection.

Question 4

Which of the following is NOT a component of the Epidemiological Triangle?

Accepted Answer

Vector

Question 5

Which of the following best describes the difference between Gram-positive and Gram-negative bacterial cell walls?

Accepted Answer

Gram-positive bacteria have a thick peptidoglycan layer and lack an outer membrane.

Question 6

Which genus is known for forming endospores, and what is the primary function of an endospore?

Accepted Answer

Bacillus; to survive harsh environmental conditions.

Question 7

A microbiologist is culturing bacteria that require high salt concentrations for growth. These bacteria are best classified as:

Accepted Answer

Halophiles

Question 8

Which of the following equations correctly calculates the number of cells ($N$) after $n$ generations, starting with $N_0$ cells?

Accepted Answer

$N = N_0 	imes 2^n$

Question 9

Which of the following best describes the mechanism of action of penicillin?

Accepted Answer

Disrupts cell wall synthesis by inhibiting peptidoglycan cross-linking.

Question 10

A patient is prescribed a broad-spectrum antibiotic. What is a potential risk associated with this treatment?

Accepted Answer

Development of a superinfection due to disruption of normal microbiota.

Question 11

Which of the following is a direct method for measuring microbial growth?

Accepted Answer

Counting colonies on a plate after serial dilution.

Question 12

Which of the following statements about acid-fast bacteria is correct?

Accepted Answer

They have waxy cell walls containing mycolic acids, as seen in Mycobacterium.

Question 13

Which of the following is the top biological vector responsible for spreading disease worldwide?

Accepted Answer

Mosquitoes

Question 14

Which of the following best describes the difference between selective and differential media?

Accepted Answer

Selective media inhibit the growth of some organisms, while differential media distinguish between organisms based on biochemical reactions.

Question 15

Which of the following is a mechanism by which bacteria can develop resistance to antibiotics?

Accepted Answer

Producing enzymes that inactivate the drug, such as $\beta$-lactamases.

Question 16

Which of the following is an example of an experimental epidemiology study?

Accepted Answer

A physician randomly assigns patients to receive either a new vaccine or a placebo and monitors disease incidence.

Question 17

Which of the following best explains why aseptic technique is important in microbiology laboratories?

Accepted Answer

It prevents contamination of cultures and protects laboratory personnel from infection.

Question 18

Which of the following chemical agents is most effective for sterilizing heat-sensitive medical equipment?

Accepted Answer

Ethylene oxide gas

Question 19

Which of the following best describes the action of ionizing radiation on microbial cells?

Accepted Answer

It produces free radicals that damage cellular molecules.

Question 20

A patient with a fungal infection is treated with a drug that targets ergosterol synthesis. This drug is most likely:

Accepted Answer

An antifungal agent such as amphotericin B.

Microbiology Exam Study Guide: Step-by-Step Guidance

Study Guide - Practice Questions