Question 1

Which of the following best distinguishes innate immunity from adaptive immunity?

Accepted Answer

Innate immunity provides immediate, non-specific defense, while adaptive immunity is slower but highly specific and develops memory.

Question 2

A patient is found to have a deficiency in antimicrobial peptides. Which of the following consequences is most likely?

Accepted Answer

Reduced ability to lyse bacterial membranes, leading to increased risk of bacterial infections.

Question 3

Which of the following is a mechanical barrier in the first line of defense against pathogens?

Accepted Answer

Mucociliary escalator in the respiratory tract

Question 4

Which leukocyte is primarily responsible for the destruction of parasitic worms and is involved in allergic responses?

Accepted Answer

Eosinophil

Question 5

Which of the following best describes the function of interferons?

Accepted Answer

They stimulate neighboring cells to produce antiviral proteins.

Question 6

A patient with a genetic defect in iron-binding proteins is most likely to experience which of the following?

Accepted Answer

Increased bacterial growth due to more available iron.

Question 7

Which of the following is NOT a cardinal sign of inflammation?

Accepted Answer

Fever

Question 8

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

Accepted Answer

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

Question 9

Which of the following best describes the role of MHC class I molecules?

Accepted Answer

They present intracellular antigens to cytotoxic T cells.

Question 10

A patient is exposed to a T-independent antigen. Which of the following is most likely to occur?

Accepted Answer

B cells can be activated without T cell help, but the response will primarily produce IgM antibodies.

Question 11

Which antibody class is most effective at activating the classical complement pathway?

Accepted Answer

IgM

Question 12

Which of the following best describes the principle of herd immunity?

Accepted Answer

Protection of unvaccinated individuals when a high percentage of the population is immune.

Question 13

Which of the following is a key reason why smallpox eradication was possible?

Accepted Answer

Smallpox infection resulted in lifelong immunity and there were no asymptomatic carriers.

Question 14

Which of the following best describes the difference between ID$$_{50}$$ and LD$$_{50}$$?

Accepted Answer

ID$$_{50} is $$the dose that infects 50% of a population, while LD$$_{50} is $$the dose that kills 50%.

Question 15

A pathogen with a basic reproduction number $$R_0 = 5$ is introduced into a population. What does this value indicate?

Accepted Answer

Each infected individual will, on average, infect 5 other individuals in a fully susceptible population.

Question 16

Which of the following is a characteristic of exotoxins?

Accepted Answer

They are proteins secreted by bacteria and can be highly specific in their action.

Question 17

Which of the following best describes the process of quorum sensing in bacteria?

Accepted Answer

Bacteria detect and respond to population density by producing and sensing signaling molecules.

Question 18

A patient develops an autoimmune disease. Which of the following best explains the underlying cause?

Accepted Answer

Failure of self-tolerance screening, leading to immune attack on the body's own tissues.

Question 19

Which of the following best describes the principle behind a sandwich ELISA?

Accepted Answer

An antigen is captured between two antibodies, one for capture and one for detection.

Question 20

Which of the following is a key difference between contact transmission and airborne transmission of pathogens?

Accepted Answer

Contact transmission involves direct or indirect physical contact, while airborne transmission involves inhalation of small particles that remain suspended in air.

Innate and Adaptive Immunity, Host-Microbe Interactions, and Biomedical Applications

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