Question 1

Which of the following best distinguishes a virus from a bacterium?

Accepted Answer

Viruses lack cellular structure and metabolic enzymes, while bacteria are cellular and metabolically active.

Question 2

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

Accepted Answer

The virus is continually present in the host, often with ongoing symptoms.

Question 3

Which of the following is a correct sequence for the pattern of disease progression?

Accepted Answer

Incubation period → prodromal period → period of illness → period of decline → period of convalescence

Question 4

The LD$$_{50} of $$botulinum toxin is $$0.03\ \mathrm{ng/kg}$$, and the LD$$_{50} of $$Salmonella toxin is $$12\ \mathrm{mg/kg}. $$Which statement is correct?

Accepted Answer

Botulinum toxin is more potent because it requires a much lower dose to kill 50% of the population.

Question 5

Which of the following best describes the role of siderophores in bacterial pathogenicity?

Accepted Answer

They bind iron from the host, making it available for bacterial growth.

Question 6

A patient develops fever, chills, and hypotension after cardiac catheterization with sterile equipment and water. The water was not tested for endotoxins. Which assay should have been used?

Accepted Answer

LAL (Limulus Amebocyte Lysate) assay

Question 7

Which of the following is a function of the complement system?

Accepted Answer

Enhancing phagocytosis through opsonization

Question 8

Which of the following best explains why the influenza vaccine does not provide long-term protection?

Accepted Answer

The influenza virus undergoes antigenic variation, changing its surface proteins frequently.

Question 9

Which of the following is an example of a T-dependent antigen response?

Accepted Answer

A protein antigen that requires TH cell activation for B cell antibody production

Question 10

Which of the following best describes the function of interferons (IFNs)?

Accepted Answer

They induce uninfected cells to produce antiviral proteins that inhibit viral replication.

Question 11

A patient receives an injection of gamma globulin after exposure to hepatitis A. What type of adaptive immunity is this?

Accepted Answer

Artificially acquired passive immunity

Question 12

Which of the following is a correct statement about Koch’s postulates?

Accepted Answer

They require that the suspected pathogen be isolated and grown in pure culture.

Question 13

Which of the following is a function of plasma cells?

Accepted Answer

They produce antibodies specific to an antigen.

Question 14

Which of the following best describes the difference between exotoxins and endotoxins?

Accepted Answer

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

Question 15

Which of the following is a correct example of microbial antagonism?

Accepted Answer

Normal microbiota outcompete pathogens for nutrients and attachment sites.

Question 16

Which of the following best describes the role of Toll-like receptors (TLRs) in innate immunity?

Accepted Answer

They recognize pathogen-associated molecular patterns (PAMPs) and activate immune responses.

Question 17

A patient is exposed to a pathogen and develops a secondary immune response upon re-exposure. Which term best describes this response?

Accepted Answer

Anamnestic response

Question 18

Which of the following is a correct statement about the function of natural killer (NK) cells?

Accepted Answer

They destroy cells that lack MHC class I molecules on their surface.

Question 19

Which of the following is a correct example of a zoonosis?

Accepted Answer

Rabies transmitted from a dog to a human

Question 20

Which of the following best describes the function of memory cells in adaptive immunity?

Accepted Answer

They persist long-term and mount a rapid response upon re-exposure to the same antigen.

BIO2440 Microbiology Study Guide – Step-by-Step Guidance

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