Question 1

Which of the following best describes the main structural difference between viruses and bacteria?

Accepted Answer

Viruses lack cellular structures such as ribosomes and a plasma membrane, while bacteria possess these components.

Question 2

A patient is diagnosed with Creutzfeldt-Jakob disease (CJD). Which of the following statements about the causative agent is correct?

Accepted Answer

CJD is caused by a misfolded protein called a prion, which lacks nucleic acids.

Question 3

Which of the following best explains the difference between lytic and lysogenic viral replication cycles?

Accepted Answer

In the lytic cycle, the host cell is lysed to release new virions, while in the lysogenic cycle, viral DNA integrates into the host genome and can remain dormant.

Question 4

Which of the following viruses is most likely to undergo antigenic shift, leading to major outbreaks or pandemics?

Accepted Answer

Influenza A virus

Question 5

A laboratory is studying a +ssRNA virus. Which of the following statements about its replication is correct?

Accepted Answer

The viral genome can serve directly as mRNA for translation by host ribosomes.

Question 6

Which of the following best describes the function of viral spikes?

Accepted Answer

They facilitate attachment to specific host cell receptors.

Question 7

A patient presents with a persistent latent viral infection. Which of the following viruses is most likely responsible?

Accepted Answer

Herpes simplex virus

Question 8

Which of the following is a key difference between foodborne infection and food poisoning?

Accepted Answer

Foodborne infection involves ingestion of live pathogens that multiply in the host, while food poisoning is caused by ingestion of preformed toxins.

Question 9

Which of the following statements about the respiratory system's defenses against infection is correct?

Accepted Answer

The mucociliary escalator helps remove trapped microbes from the respiratory tract.

Question 10

A patient is diagnosed with Streptococcus pneumoniae infection. Which of the following is a major virulence factor for this organism?

Accepted Answer

Polysaccharide capsule

Question 11

Which of the following best describes the difference between roundworms and flatworms?

Accepted Answer

Roundworms are cylindrical and unsegmented, while flatworms are dorsoventrally flattened and may be segmented.

Question 12

Which of the following protozoans is most commonly associated with waterborne outbreaks of diarrhea in the United States?

Accepted Answer

Cryptosporidium

Question 13

A patient presents with severe watery diarrhea after recent antibiotic use. Which organism is most likely responsible?

Accepted Answer

Clostridioides difficile

Question 14

Which of the following best describes the role of the digestive system's microbiome in preventing infection?

Accepted Answer

It competes with pathogens for nutrients and attachment sites, producing substances that inhibit pathogen growth.

Question 15

A 5-year-old child develops a barking cough and inspiratory stridor. Which virus is most likely responsible?

Accepted Answer

Human parainfluenza virus (HPIV)

Question 16

Which of the following statements about antigenic drift and antigenic shift is correct?

Accepted Answer

Antigenic shift involves major genetic reassortment, while antigenic drift involves minor point mutations.

Question 17

A patient is diagnosed with hepatitis B. Which of the following best describes the genome of hepatitis B virus?

Accepted Answer

Partially double-stranded DNA

Question 18

Which of the following is the correct definition of a definitive host in a parasitic life cycle?

Accepted Answer

The host in which the parasite undergoes sexual reproduction

Question 19

A patient presents with a cough, fever, and chest pain. Sputum culture reveals acid-fast bacilli. Which organism is most likely responsible?

Accepted Answer

Mycobacterium tuberculosis

Question 20

A 30-year-old traveler develops profuse, rice-water diarrhea after visiting a region with poor sanitation. Which organism is most likely responsible?

Accepted Answer

Vibrio cholerae

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