Question 1

Which of the following best explains why protozoa, algae, and nonmicrobial parasitic worms are studied in microbiology?

Accepted Answer

They are all microscopic during at least one stage of their life cycle.

Question 2

A patient is diagnosed with a persistent viral infection. Which of the following best describes the pattern of virion abundance in this type of infection?

Accepted Answer

Virion levels fluctuate, with periods of low-level production over a long duration.

Question 3

Which of the following statements correctly compares Gram-positive and Gram-negative bacterial cell walls?

Accepted Answer

Gram-positive bacteria have teichoic acids in their cell walls, while Gram-negative bacteria have lipopolysaccharides in their outer membrane.

Question 4

During aerobic respiration, what is the net ATP yield from the complete oxidation of one molecule of glucose, and which equation best represents the overall process?

Accepted Answer

38 ATP; $$ \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\ \mathrm{O}_2 ightarrow 6\ \mathrm{CO}_2 + 6\ \mathrm{H}_2\mathrm{O} + 	ext{energy} $$

Question 5

A microbiologist is trying to identify an unknown bacterium by its fermentation end-products. Which of the following is a common end-product of bacterial fermentation used in identification?

Accepted Answer

Lactic acid

Question 6

Which of the following best describes the role of chemiosmosis in oxidative phosphorylation?

Accepted Answer

It uses a proton gradient across a membrane to drive ATP synthesis via ATP synthase.

Question 7

A patient is infected with a bacterium that thrives at 37°C and is sensitive to high salt concentrations. Which category does this bacterium most likely belong to?

Accepted Answer

Mesophile

Question 8

Which of the following statements about bacterial conjugation is correct?

Accepted Answer

Hfr cells can transfer chromosomal genes to recipient cells via a pilus.

Question 9

Which of the following physical methods achieves sterilization by removing, rather than killing, microorganisms?

Accepted Answer

Filtration

Question 10

A hospital is deciding between using moist heat (autoclave) and dry heat (oven) for sterilization. Which of the following is an advantage of using an autoclave?

Accepted Answer

It sterilizes more quickly and at lower temperatures than dry heat.

Question 11

Which of the following best describes the principle of selective toxicity in antimicrobial drugs?

Accepted Answer

The drug inhibits or kills the pathogen without harming the host.

Question 12

A patient develops a secondary infection with Candida albicans after taking broad-spectrum antibiotics. This is an example of:

Accepted Answer

Opportunistic infection

Question 13

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

Accepted Answer

Producing enzymes that inactivate the drug

Question 14

Which of the following best describes the difference between sterilization and disinfection?

Accepted Answer

Sterilization removes all forms of microbial life, while disinfection removes most pathogens but not endospores.

Question 15

Which of the following is a correct statement about the human microbiome?

Accepted Answer

Transient microbiota are present for a short time and do not permanently colonize the host.

Question 16

Which of the following is a function of the complement system in innate immunity?

Accepted Answer

Forming membrane attack complexes that lyse pathogens

Question 17

A patient receives an injection of pre-formed antibodies against tetanus toxin. Which type of immunity is this?

Accepted Answer

Artificially acquired passive immunity

Question 18

Which of the following best describes the structure and function of bacterial endospores?

Accepted Answer

They are dormant, highly resistant structures formed in response to harsh conditions.

Question 19

Which of the following statements about attenuated (live) vaccines is correct?

Accepted Answer

They can cause mild infection and provide long-lasting immunity.

Question 20

A patient is exposed to a pathogen through a cut in the skin. Which portal of entry is involved?

Accepted Answer

Parenteral route

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