Question 1

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

Accepted Answer

Innate immunity provides a rapid, non-specific response to a broad range of pathogens, while adaptive immunity is slower but highly specific and results in immune memory.

Question 2

A patient is given a vaccine containing inactivated virus. Which type of immunity is primarily being induced?

Accepted Answer

Artificial active immunity

Question 3

Which of the following is NOT a function of the complement system?

Accepted Answer

Activation of B cells to produce antibodies

Question 4

A child with a genetic defect in the formation of tight junctions between epithelial cells would be most susceptible to which of the following?

Accepted Answer

Increased risk of pathogen invasion through compromised physical barriers

Question 5

Which of the following best explains why infants are more susceptible to gastrointestinal infections than adults?

Accepted Answer

The intestinal microbiota in infants is immature, providing less competitive exclusion of pathogens.

Question 6

A researcher is studying a bacterial pathogen that is highly resistant to phagocytosis. Which of the following is the most likely explanation for this resistance?

Accepted Answer

The bacterium produces a thick capsule that prevents interaction with phagocyte receptors.

Question 7

Which of the following statements about pattern recognition receptors (PRRs) and pathogen-associated molecular patterns (PAMPs) is correct?

Accepted Answer

PRRs on phagocytes recognize PAMPs on pathogens, triggering phagocytosis and immune activation.

Question 8

A patient is exposed to a bacterial endotoxin (lipid A of LPS). Which of the following is the most likely immune response?

Accepted Answer

Activation of TLR-4 on phagocytes, leading to production of proinflammatory cytokines and possible fever.

Question 9

Which of the following best describes the process of clonal deletion in T cell development?

Accepted Answer

Elimination of T cells that bind too strongly to self-peptide:self-MHC complexes, preventing autoimmunity.

Question 10

A patient receives an injection of antiserum containing antibodies against tetanus toxin after a puncture wound. Which type of immunity is this?

Accepted Answer

Artificial passive immunity

Question 11

Which of the following is a key feature of the secondary antibody response compared to the primary response?

Accepted Answer

It is characterized by a rapid and robust production of high-affinity IgG (or IgA) antibodies due to memory B cells.

Question 12

Which of the following best explains why the membrane attack complex (MAC) formed by complement is more effective against gram-negative than gram-positive bacteria?

Accepted Answer

Gram-negative bacteria have an outer membrane accessible to MAC, while the thick cell wall of gram-positive bacteria prevents MAC from reaching the cytoplasmic membrane.

Question 13

A patient with a deficiency in the production of interleukin-1 (IL-1) would most likely exhibit which of the following symptoms during infection?

Accepted Answer

Reduced fever response and impaired local inflammation

Question 14

Which of the following best describes the role of opsonization in the immune response?

Accepted Answer

Opsonization is the process by which pathogens are coated with host proteins such as antibodies or C3b, enhancing their recognition and uptake by phagocytes.

Question 15

A mutation in the gene encoding the J chain peptide would most directly affect which immunoglobulin class and function?

Accepted Answer

IgM; formation of pentameric structure and efficient agglutination

Question 16

Which of the following best explains the enormous diversity of antibodies produced by B cells?

Accepted Answer

Antibody diversity is generated by random recombination of V, D, and J gene segments, junctional diversity, and somatic hypermutation.

Question 17

A patient with a genetic defect in the production of the MyD88 adaptor protein would most likely have impaired:

Accepted Answer

Signal transduction from TLRs leading to cytokine production

Question 18

Which of the following scenarios best illustrates the concept of immune tolerance?

Accepted Answer

A B cell that binds to a self-antigen in the bone marrow undergoes apoptosis and is removed from the repertoire.

Question 19

Which of the following is a direct result of the interaction between a T-helper (Th) cell and a B cell presenting antigen on MHC class II?

Accepted Answer

The B cell undergoes clonal expansion and differentiates into plasma cells and memory B cells.

Question 20

A patient is infected with a virus that specifically destroys dendritic cells. Which aspect of the immune response would be most directly impaired?

Accepted Answer

Activation of naive T cells and initiation of adaptive immunity

Innate and Adaptive Immunity: Mechanisms, Cells, and Molecular Basis

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