Question 1

Which of the following best describes the difference between mutualism and commensalism in the context of the human microbiome?

Accepted Answer

In mutualism, both the microbe and the host benefit, whereas in commensalism, the microbe benefits and the host is neither helped nor harmed.

Question 2

A patient develops a wound infection with Clostridium perfringens. Which property of this bacterium makes infection control particularly challenging in healthcare settings?

Accepted Answer

It forms endospores, which are highly resistant to heat, desiccation, and disinfectants.

Question 3

Which of the following correctly lists the taxonomic hierarchy from most inclusive to least inclusive?

Accepted Answer

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Question 4

A patient with HIV develops oral thrush caused by Candida albicans. This scenario best illustrates which of the following concepts?

Accepted Answer

Opportunistic pathogen and dysbiosis

Question 5

Which of the following statements about Gram-negative bacteria is correct and explains why they are often harder to treat with antibiotics?

Accepted Answer

They possess an outer membrane containing lipopolysaccharide (LPS), which acts as a barrier to many antibiotics.

Question 6

A norovirus outbreak occurs in a hospital. Which statement is true regarding norovirus and its implications for infection control?

Accepted Answer

Norovirus is a naked virus, making it resistant to alcohol-based disinfectants and requiring enhanced cleaning protocols.

Question 7

Which of the following best describes Koch’s postulates and their application in modern microbiology?

Accepted Answer

They are a set of criteria used to establish a causative relationship between a microbe and a disease.

Question 8

Which of the following is a key difference between bacterial endospores and fungal spores?

Accepted Answer

Bacterial endospores are primarily for survival under harsh conditions, while fungal spores are mainly for reproduction.

Question 9

A patient presents with fever (measured at 39°C), sore throat, and swollen lymph nodes. According to clinical definitions, which of the following is a sign?

Accepted Answer

Fever

Question 10

Which of the following best explains why RNA viruses evolve more rapidly than DNA viruses?

Accepted Answer

RNA-dependent RNA polymerases lack proofreading ability, leading to higher mutation rates.

Question 11

Which of the following laboratory techniques is most appropriate for identifying a protozoan infection in a patient sample?

Accepted Answer

Microscopic examination of stained specimens

Question 12

Which of the following best describes the function of bacterial fimbriae?

Accepted Answer

They facilitate attachment to surfaces and host tissues.

Question 13

A hospital is experiencing an increase in healthcare-acquired infections (HAIs) caused by antibiotic-resistant bacteria. Which of the following is a major reason healthcare settings are considered 'hot zones' for such pathogens?

Accepted Answer

High antibiotic usage and close proximity of immunocompromised patients facilitate the selection and spread of resistant strains.

Question 14

Which of the following best defines the term 'virulence factor'?

Accepted Answer

A molecule or structure produced by a microbe that enhances its ability to cause disease.

Question 15

Which of the following is a correct comparison between exotoxins and endotoxins?

Accepted Answer

Exotoxins are secreted proteins with specific targets, while endotoxins are lipopolysaccharides released from Gram-negative bacteria upon cell lysis.

Question 16

A patient is diagnosed with an infection caused by Mycobacterium tuberculosis. Which laboratory staining technique is most appropriate for identifying this organism, and why?

Accepted Answer

Acid-fast stain, because the cell wall contains mycolic acids that retain the primary stain even after acid-alcohol decolorization.

Question 17

Which of the following best describes the difference between antigenic drift and antigenic shift in influenza viruses?

Accepted Answer

Antigenic drift involves gradual accumulation of mutations, while antigenic shift involves reassortment of genome segments leading to major changes.

Question 18

Which of the following is a defining feature of eukaryotic cells that distinguishes them from prokaryotic cells?

Accepted Answer

Presence of a membrane-bound nucleus

Question 19

A patient is infected with a virus that can only infect liver cells. This specificity is best described by which term?

Accepted Answer

Tropism

Question 20

Which of the following equations correctly converts 2.5 micrometers ($$\mum) to $$nanometers (nm)?

Accepted Answer

$$2.5\ \mu\mathrm{m} 	imes 1000 = 2500\ \mathrm{nm}$$

MMG1650 Exam 1 Study Guide: Foundations of Microbiology

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Study guide - Flashcard