Question 1

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

Accepted Answer

Viruses lack both ribosomes and metabolic enzymes, while bacteria possess both.

Question 2

A researcher is culturing animal viruses and needs a cell line that can be maintained for many generations. Which type of cell line should they use, and why?

Accepted Answer

Continuous cell lines, because they can be subcultured indefinitely.

Question 3

Which of the following best describes the difference between the lytic and lysogenic cycles of bacteriophages?

Accepted Answer

The lytic cycle results in immediate lysis of the host cell, while the lysogenic cycle integrates the phage DNA into the host genome without immediate lysis.

Question 4

A patient is diagnosed with shingles years after recovering from chickenpox. Which type of infection does this represent?

Accepted Answer

Latent viral infection

Question 5

Which of the following is a function shared by both capsules and M proteins in bacterial pathogenicity?

Accepted Answer

They help bacteria evade phagocytosis by host immune cells.

Question 6

A patient develops fever and chills after cardiac catheterization, but the water and catheters used were sterile. Which test should have been performed to detect the likely cause of these symptoms?

Accepted Answer

Limulus Amebocyte Lysate (LAL) assay

Question 7

Which of the following best describes the mechanism of action of A-B toxins?

Accepted Answer

The B component binds to the host cell, allowing the A component to enter and disrupt cellular function.

Question 8

Which of the following statements about the complement system is correct?

Accepted Answer

It can be activated by three pathways: classical, alternative, and lectin.

Question 9

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

Accepted Answer

Artificially acquired passive immunity

Question 10

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

Accepted Answer

Influenza viruses undergo frequent antigenic variation.

Question 11

Which of the following is the correct sequence in the pattern of disease progression?

Accepted Answer

Incubation period, prodromal period, period of illness, period of decline, period of convalescence

Question 12

A bacterial toxin has an $$LD_{50} of$$ $$0.03\ \mathrm{ng/kg}$$, while another has an $$LD_{50} of$$ $$12\ \mathrm{mg/kg}. $$Which statement is correct?

Accepted Answer

The toxin with $$LD_{50} = 0.03\ \mathrm{ng/kg} is $$more potent.

Question 13

Which of the following is a function of siderophores in bacterial infections?

Accepted Answer

They bind and sequester iron from the host, aiding bacterial growth.

Question 14

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 15

A patient is exposed to a pathogen and develops antibodies after recovering from the infection. Which type of immunity is this?

Accepted Answer

Naturally acquired active immunity

Question 16

Which class of antibody is most likely to protect you from a common cold?

Accepted Answer

IgA

Question 17

Which of the following is a primary function of natural killer (NK) cells?

Accepted Answer

They destroy cells that lack MHC class I molecules.

Question 18

Which of the following is a correct statement about the difference between exotoxins and endotoxins?

Accepted Answer

Exotoxins are proteins secreted by bacteria, while endotoxins are lipopolysaccharides found in the outer membrane of Gram-negative bacteria.

Question 19

A hospital infection control officer investigates an outbreak of food poisoning and finds that 39 ill employees ate green beans, while 34 healthy employees did not. What type of epidemiological investigation is this?

Accepted Answer

Analytical epidemiology

Question 20

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

Accepted Answer

They are cytokines that interfere with viral replication in host cells.

Exam 2

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Study Guide - Flashcards