Question 1

Which of the following best describes the difference between innate and adaptive immunity?

Accepted Answer

Innate immunity is present at birth and responds rapidly, while adaptive immunity develops over time and is specific to particular antigens.

Question 2

Which cell type is primarily responsible for antibody production in the adaptive immune response?

Accepted Answer

B cells

Question 3

A patient with a deficiency in complement proteins is most likely to have impaired which of the following host defense functions?

Accepted Answer

Opsonization, inflammation, and cytolysis

Question 4

Which of the following best describes the role of pattern recognition receptors (PRRs) during phagocytosis?

Accepted Answer

PRRs recognize conserved microbial structures, promoting adherence and ingestion by phagocytes.

Question 5

Leishmania donovani is able to evade phagocytosis by which mechanism?

Accepted Answer

Inhibiting fusion of the phagosome with the lysosome

Question 6

Which of the following statements about the classical and alternative pathways of complement activation is correct?

Accepted Answer

The classical pathway is triggered by antigen-antibody complexes, while the alternative pathway is triggered by microbial surfaces.

Question 7

Which cytokine is most associated with the development of a cytokine storm?

Accepted Answer

Interleukin-6 (IL-6)

Question 8

Which lymphoid organ is the primary site for T cell maturation?

Accepted Answer

Thymus

Question 9

Which region of an antibody is responsible for binding to antigens?

Accepted Answer

Variable region

Question 10

Genetic recombination in B cells is essential for antibody diversity. Which process is directly involved in this mechanism?

Accepted Answer

V(D)J recombination

Question 11

Which class of antibody is most abundant in serum and is responsible for secondary immune responses?

Accepted Answer

IgG

Question 12

A patient is exposed to Trypanosoma brucei, which evades the immune system by changing its surface glycoproteins. This is an example of:

Accepted Answer

Antigenic variation

Question 13

Which of the following best describes the difference between MHC I and MHC II molecules?

Accepted Answer

MHC I is found on all nucleated cells and presents endogenous antigens to cytotoxic T cells; MHC II is found on antigen-presenting cells and presents exogenous antigens to helper T cells.

Question 14

Which cell surface marker is characteristic of T helper cells?

Accepted Answer

CD4

Question 15

During the primary cell-mediated response (Th1), which cytokine is most important for activating cytotoxic T cells?

Accepted Answer

Interferon-gamma (IFN-\gamma)

Question 16

Which process allows B cells to produce antibodies with different constant regions while maintaining antigen specificity?

Accepted Answer

Class switching

Question 17

A person receives a vaccine containing inactivated virus. Which type of immunity is being acquired?

Accepted Answer

Artificially acquired active immunity

Question 18

Which of the following is a function of antibodies that directly leads to the destruction of pathogens via the complement system?

Accepted Answer

Complement fixation

Question 19

Which of the following best explains why memory cells are important in the secondary immune response?

Accepted Answer

They allow for a faster and stronger response upon re-exposure to the same antigen.

Question 20

A patient with a fever is experiencing an innate immune response. Which equation best represents the relationship between body temperature ($$T) $$and the rate of pathogen replication ($$R$$), assuming that higher temperature inhibits replication?

Accepted Answer

$$R = \frac{1}{T}$$

Study Guidance for Host Defenses (Immunology) – Microbiology

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