Q: Which equation correctly represents the conversion of glucose to lactic acid during anaerobic fermentation by bacteria?

$$\text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{C}_3\text{H}_6\text{O}_3$$

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 cytoplasm, while bacteria possess these components.

Question 2

A patient presents with rapidly progressive dementia and myoclonus. Brain biopsy reveals spongiform changes. Which of the following best describes the structure of the infectious agent responsible for Creutzfeldt-Jakob disease?

Accepted Answer

A misfolded protein lacking nucleic acids.

Question 3

Which step in the viral replication cycle is unique to retroviruses?

Accepted Answer

Reverse transcription of viral RNA into DNA using the enzyme reverse transcriptase: $$	ext{RNA} ightarrow 	ext{DNA}$$

Question 4

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

Accepted Answer

Lytic replication results in immediate destruction of the host cell, while lysogenic replication involves integration of viral DNA into the host genome and delayed cell lysis.

Question 5

Antigenic shift and antigenic drift are important concepts in influenza outbreaks. Which statement correctly distinguishes these two processes?

Accepted Answer

Antigenic shift involves major changes due to reassortment of viral genome segments, while antigenic drift involves minor mutations in viral genes.

Question 6

Which of the following viruses is considered latent and can reactivate later in life, causing shingles?

Accepted Answer

Varicella-zoster virus (VZV)

Question 7

A bacteriophage is best described as:

Accepted Answer

A virus that infects bacteria.

Question 8

Which structure in the respiratory system is most important in preventing microbial infection by trapping particles and moving them out of the airways?

Accepted Answer

Ciliated epithelial cells and mucus

Question 9

A patient develops pneumonia after exposure to contaminated water in a hotel air conditioning system. Which organism is most likely responsible?

Accepted Answer

Legionella pneumophila

Question 10

Which of the following is a notable virulence factor of Streptococcus pyogenes that allows it to evade phagocytosis?

Accepted Answer

M protein

Question 11

Which vaccine type is available for influenza and provides the broadest protection against multiple strains?

Accepted Answer

Quadrivalent inactivated vaccine

Question 12

Which of the following best describes the difference between foodborne infection and food poisoning?

Accepted Answer

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

Question 13

Which of the following protozoans is most commonly associated with outbreaks of diarrhea in daycare centers and is transmitted via cysts in contaminated water?

Accepted Answer

Giardia lamblia

Question 14

Which equation correctly represents the conversion of glucose to lactic acid during anaerobic fermentation by bacteria?

Accepted Answer

$$	ext{C}_6	ext{H}_{12}	ext{O}_6 ightarrow 2	ext{C}_3	ext{H}_6	ext{O}_3$$

Question 15

Which of the following is a roundworm (nematode) that can cause intestinal infection and is commonly transmitted via ingestion of eggs from contaminated soil?

Accepted Answer

Ascaris lumbricoides

Question 16

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

Accepted Answer

Clostridioides difficile

Question 17

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

Accepted Answer

Competes with pathogens for nutrients and produces antimicrobial substances.

Question 18

Which hepatitis virus is transmitted primarily via the fecal-oral route and does NOT cause chronic infection?

Accepted Answer

Hepatitis A virus

Question 19

Which of the following is a flatworm (cestode) that can cause human infection through ingestion of undercooked fish?

Accepted Answer

Diphyllobothrium latum

Question 20

A patient presents with bloody diarrhea after traveling to a developing country. Stool microscopy reveals trophozoites with ingested red blood cells. Which protozoan is most likely responsible?

Accepted Answer

Entamoeba histolytica

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