Question 1

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

Accepted Answer

Endotoxins are lipopolysaccharides found in the outer membrane of Gram-negative bacteria, while exotoxins are proteins secreted by both Gram-positive and Gram-negative bacteria.

Question 2

A patient develops a fever and low blood pressure after receiving an intravenous injection of antibiotics to treat a Gram-negative bacterial infection. Which microbial component is most likely responsible for these symptoms?

Accepted Answer

Lipopolysaccharide (LPS)

Question 3

Which of the following is NOT considered a physical barrier in innate immunity?

Accepted Answer

Lysozyme in tears

Question 4

Which of the following best explains why normal microbiota are important for preventing pathogen colonization?

Accepted Answer

They compete with pathogens for nutrients and attachment sites, limiting pathogen growth.

Question 5

A child receives a vaccine containing inactivated virus particles. Which type of immunity is being induced?

Accepted Answer

Artificial active immunity

Question 6

Which of the following is a function of cytotoxic T cells (CD8+)?

Accepted Answer

Destruction of virus-infected cells by releasing perforin and granzymes

Question 7

Which of the following statements about superantigens is correct?

Accepted Answer

Superantigens cause massive, non-specific activation of T cells, leading to excessive cytokine release.

Question 8

Which of the following is an example of a chemical barrier in innate immunity?

Accepted Answer

Low pH of gastric juice in the stomach

Question 9

A patient is diagnosed with Clostridium botulinum infection. Which type of toxin is responsible for the symptoms, and what is its mechanism?

Accepted Answer

Exotoxin; blocks acetylcholine release at neuromuscular junctions

Question 10

Which of the following best describes the process of opsonization?

Accepted Answer

Coating of pathogens with antibodies or complement proteins to enhance phagocytosis

Question 11

Which of the following is a correct sequence of events in the inflammatory response?

Accepted Answer

Vasodilation → increased vascular permeability → phagocyte migration → tissue repair

Question 12

Which of the following is a characteristic of adaptive immunity that distinguishes it from innate immunity?

Accepted Answer

Memory for previously encountered antigens

Question 13

A patient receives an injection of pre-formed antibodies after exposure to rabies virus. Which type of immunity is this?

Accepted Answer

Artificial passive immunity

Question 14

Which of the following best explains why fever can be beneficial during infection?

Accepted Answer

Fever enhances the activity of immune cells and inhibits growth of some pathogens.

Question 15

Which of the following is an example of artificial active immunity?

Accepted Answer

Receiving a vaccine against measles

Question 16

Which of the following is a function of helper T cells (CD4+)?

Accepted Answer

Activating B cells and cytotoxic T cells by releasing cytokines

Question 17

Which of the following is a correct statement about the role of MHC (Major Histocompatibility Complex) molecules in adaptive immunity?

Accepted Answer

MHC molecules present antigens to T cells, allowing recognition of infected or abnormal cells.

Question 18

Which of the following best describes the difference between primary and secondary immune responses?

Accepted Answer

The secondary response is faster and stronger due to the presence of memory cells.

Question 19

A patient with a genetic defect cannot produce complement proteins. Which of the following immune functions would be most directly impaired?

Accepted Answer

Opsonization and formation of the membrane attack complex to lyse pathogens

Question 20

Which of the following is a correct example of a disease caused by immune system attacking self-antigens (autoimmunity)?

Accepted Answer

Type 1 diabetes, where T cells attack pancreatic beta cells

Study Guide: Microbial Infection, Immunity, and Biotechnology

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