Question 1

Which of the following best describes the main difference between prokaryotic and eukaryotic cells?

Accepted Answer

Eukaryotic cells have a nucleus, while prokaryotic cells lack a true nucleus.

Question 2

A patient presents with a bacterial infection. The Gram stain reveals pink, rod-shaped bacteria. What does this indicate about the bacterial cell wall?

Accepted Answer

The bacteria have a thin peptidoglycan layer and an outer membrane.

Question 3

Which of the following is a correct application of Koch’s postulates in identifying the causative agent of a disease?

Accepted Answer

Demonstrate that the suspected pathogen can be grown in pure culture and causes disease when introduced into a healthy host.

Question 4

Which of the following best describes the role of normal flora in human health?

Accepted Answer

Normal flora compete with pathogens and help prevent infections.

Question 5

A laboratory technician is using a differential medium to distinguish between two bacterial species. What is the primary purpose of this medium?

Accepted Answer

To distinguish between species based on metabolic or biochemical characteristics.

Question 6

Which of the following statements about antimicrobial drug resistance is correct?

Accepted Answer

Drug resistance occurs when bacteria acquire genes that allow them to survive exposure to antibiotics.

Question 7

Which phase of the bacterial growth curve is characterized by the equation $$N_t = N_0$ e$$^{\mu t}$$, where N_t$ is the number of cells at time t$, N_0$ is the initial number of cells, and $$\mu$$ is the growth rate?

Accepted Answer

Log (exponential) phase

Question 8

Which of the following is a virulence factor that helps bacteria evade the host immune system?

Accepted Answer

Capsule formation

Question 9

A patient is diagnosed with a viral infection. Which of the following statements about viruses is correct?

Accepted Answer

Viruses require a host cell to replicate.

Question 10

Which of the following best describes the principle of antisepsis?

Accepted Answer

The use of chemical agents on living tissue to inhibit or destroy pathogens.

Question 11

A specimen is collected for bacterial culture. Which of the following variables is most likely to affect the quality of the specimen?

Accepted Answer

The time between collection and processing.

Question 12

Which of the following is the correct order of the Gram stain procedure?

Accepted Answer

Crystal violet, iodine, alcohol, safranin

Question 13

Which of the following best explains why hand hygiene is critical in healthcare settings?

Accepted Answer

It prevents the transmission of both normal flora and pathogens between patients.

Question 14

Which of the following is an example of a physical requirement for microbial growth?

Accepted Answer

Optimal temperature

Question 15

Which of the following best describes an opportunistic pathogen?

Accepted Answer

A microbe that causes disease only when the host’s defenses are compromised.

Question 16

Which of the following is a correct statement about the use of selective media in microbiology?

Accepted Answer

Selective media inhibit the growth of certain microbes while allowing others to grow.

Question 17

Which of the following equations correctly represents the calculation of generation time ($$g) in $$bacterial growth, given the number of generations ($$n) $$and total time ($$t$$)?

Accepted Answer

$$g = \frac{t}{n}$$

Question 18

Which of the following is the best definition of pathogenicity?

Accepted Answer

The ability of a microbe to cause disease.

Question 19

Which of the following is a correct statement about the use of metabolic and enzymatic testing in microbiology?

Accepted Answer

These tests are used to identify bacteria based on their biochemical activities.

Question 20

A patient is suspected of having a respiratory infection. Which of the following is the most important consideration when collecting a sputum specimen?

Accepted Answer

Collect the specimen before antibiotic therapy begins.

BIO 125 Introductory Microbiology – Syllabus and Core Concepts

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