Adaptive immunity Knowledge-Based Download PDF

Questions

1. 1.

   Which mechanism is directly responsible for generating the vast diversity of antigen receptor specificities on naive B and T lymphocytes prior to antigen exposure?

   • A) Somatic recombination of variable, diversity, and joining gene segments
   • B) Somatic hypermutation induced by antigen presentation in germinal centers
   • C) Alternative RNA splicing of constant region exons in mature plasma cells
   • D) Receptor remodeling initiated by pathogen-associated molecular patterns
2. 2.

   Which cell-surface proteins on professional antigen-presenting cells display exogenous peptide fragments to initiate the activation of helper T (CD4+) lymphocytes?

   • A) Class II major histocompatibility complex (MHC class II) molecules
   • B) Class I major histocompatibility complex (MHC class I) molecules
   • C) Toll-like receptor (TLR) complexes
   • D) Membrane attack complex (MAC) proteins
3. 3.

   Compared to a primary immune response, what directly enables the adaptive immune system to mount a faster and significantly larger antibody response upon re-exposure to the same antigen?

   • A) Immediate activation of nonspecific natural killer cells that produce circulating immunoglobulins.
   • B) Rapid differentiation of naive helper T cells that permanently circulate in elevated baseline numbers.
   • C) Persistence of antigen-specific memory B cells that rapidly proliferate and differentiate into plasma cells.
   • D) Continuous high-level secretion of antibodies by short-lived effector cells throughout the individual's lifespan.
4. 4.

   In the cell-mediated branch of adaptive immunity, how do cytotoxic T lymphocytes primarily eliminate host cells infected with intracellular pathogens?

   • A) By secreting free immunoglobulins that neutralize extracellular viral particles
   • B) By releasing histamine and heparin to trigger localized inflammatory responses
   • C) By engulfing intact infected host cells through receptor-mediated phagocytosis
   • D) By releasing perforins and granzymes that induce apoptosis in target cells displaying foreign antigens on MHC class I molecules
5. 5.

   Which of the following processes is a defining characteristic of humoral immunity within the human adaptive immune system?

   • A) Direct destruction of virally infected host cells by cytotoxic T lymphocytes
   • B) Secretion of antigen-specific antibodies by differentiated plasma cells into bodily fluids
   • C) Rapid phagocytosis of foreign particles by circulating neutrophils and monocytes
   • D) Display of endogenous peptide fragments on MHC class I molecules to activate CD8+ T cells