,BIOD 331 Module 3 | Pathophysiology | Portage
Learning | Q & A| 2026 Edition
1. Which of the following best describes the role of the skin as a physical barrier against
microorganisms?
A) Its neutral pH and moist environment promote microbial growth
B) The stratum corneum consists of dead, keratinized cells that are continuously shed, physically
removing adherent microorganisms
C) It relies solely on antimicrobial peptides without any structural defense
D) It lacks any chemical properties that inhibit microbial colonization
Correct Answer: The stratum corneum consists of dead, keratinized cells that are continuously shed,
physically removing adherent microorganisms
Rationale: The skin's epidermis has multiple layers of tightly packed epithelial cells, with the outermost
stratum corneum consisting of dead, keratinized cells that are continuously shed. Additionally, the skin's
acidic pH (4-6), antimicrobial peptides, and enzymes like lysozyme create an inhospitable environment.
The skin acts as the body's primary physical barrier against microbial invasion.
2. Innate immunity is characterized by which of the following features?
A) Antigen specificity and immunological memory
B) Immediate response to conserved microbial structures
C) Long-lasting protection after subsequent exposures
D) Reliance on B and T lymphocytes for function
Correct Answer: Immediate response to conserved microbial structures
Rationale: Innate immunity provides immediate, non-specific defense against pathogens by recognizing
conserved microbial structures. Adaptive immunity is distinguished by antigen specificity, immunological
memory, and tailored responses involving B and T lymphocytes.
3. Helper T cells (CD4+ T cells) are classified as part of which branch of the immune system?
,A) Innate immunity
B) Adaptive immunity
C) First line of defense
D) Physical barriers
Correct Answer: Adaptive immunity
Rationale: Helper T cells (CD4+ T cells) are central to the adaptive immune response, functioning to
activate and direct other immune cells. They recognize specific antigens presented by antigen-
presenting cells and require prior activation, distinguishing them from innate immune cells.
4. Which cell type is the first responder to phagocytose a foreign invader during the acute inflammatory
response?
A) Macrophage
B) Lymphocyte
C) Neutrophil
D) Mast cell
Correct Answer: Neutrophil
Rationale: Neutrophils are the most abundant leukocytes in peripheral blood and act as the body's first
line of cellular defense during the acute inflammatory response. They rapidly migrate to infection sites,
where they phagocytose pathogens and debris.
5. Which of the following hypersensitivity reactions is mediated by IgE antibodies and is responsible for
anaphylaxis?
A) Type I hypersensitivity
B) Type II hypersensitivity
C) Type III hypersensitivity
D) Type IV hypersensitivity
, Correct Answer: Type I hypersensitivity
Rationale: Type I hypersensitivity reactions are IgE-mediated and are responsible for anaphylaxis,
allergic rhinitis, and asthma. Type II reactions are antibody-mediated (IgG/IgM), Type III are immune-
complex mediated, and Type IV are T-cell mediated (delayed-type hypersensitivity).
6. Autoimmune disorders present significant diagnostic challenges primarily because:
A) They always present with the same symptoms in every patient
B) There is a single definitive test for all autoimmune diseases
C) Over 80 distinct autoimmune diseases exist with overlapping, nonspecific symptoms
D) Serological markers are 100% specific and sensitive
Correct Answer: Over 80 distinct autoimmune diseases exist with overlapping, nonspecific symptoms
Rationale: Over 80 distinct autoimmune diseases are recognized, many presenting with nonspecific
symptoms such as fatigue, fever, joint pain, and rashes that overlap with multiple conditions. Serological
markers lack absolute specificity, and there is no single definitive test for most autoimmune diseases.
7. What is the function of antigen-presenting cells (APCs) in the immune response?
A) To directly kill infected cells
B) To process and present antigens to T cells
C) To produce antibodies against pathogens
D) To release histamine during allergic reactions
Correct Answer: To process and present antigens to T cells
Rationale: Antigen-presenting cells (APCs) process antigens and present them on their surface via MHC
molecules to T cells. This is essential for initiating adaptive immune responses. B cells produce
antibodies, cytotoxic T cells kill infected cells, and mast cells release histamine.
Learning | Q & A| 2026 Edition
1. Which of the following best describes the role of the skin as a physical barrier against
microorganisms?
A) Its neutral pH and moist environment promote microbial growth
B) The stratum corneum consists of dead, keratinized cells that are continuously shed, physically
removing adherent microorganisms
C) It relies solely on antimicrobial peptides without any structural defense
D) It lacks any chemical properties that inhibit microbial colonization
Correct Answer: The stratum corneum consists of dead, keratinized cells that are continuously shed,
physically removing adherent microorganisms
Rationale: The skin's epidermis has multiple layers of tightly packed epithelial cells, with the outermost
stratum corneum consisting of dead, keratinized cells that are continuously shed. Additionally, the skin's
acidic pH (4-6), antimicrobial peptides, and enzymes like lysozyme create an inhospitable environment.
The skin acts as the body's primary physical barrier against microbial invasion.
2. Innate immunity is characterized by which of the following features?
A) Antigen specificity and immunological memory
B) Immediate response to conserved microbial structures
C) Long-lasting protection after subsequent exposures
D) Reliance on B and T lymphocytes for function
Correct Answer: Immediate response to conserved microbial structures
Rationale: Innate immunity provides immediate, non-specific defense against pathogens by recognizing
conserved microbial structures. Adaptive immunity is distinguished by antigen specificity, immunological
memory, and tailored responses involving B and T lymphocytes.
3. Helper T cells (CD4+ T cells) are classified as part of which branch of the immune system?
,A) Innate immunity
B) Adaptive immunity
C) First line of defense
D) Physical barriers
Correct Answer: Adaptive immunity
Rationale: Helper T cells (CD4+ T cells) are central to the adaptive immune response, functioning to
activate and direct other immune cells. They recognize specific antigens presented by antigen-
presenting cells and require prior activation, distinguishing them from innate immune cells.
4. Which cell type is the first responder to phagocytose a foreign invader during the acute inflammatory
response?
A) Macrophage
B) Lymphocyte
C) Neutrophil
D) Mast cell
Correct Answer: Neutrophil
Rationale: Neutrophils are the most abundant leukocytes in peripheral blood and act as the body's first
line of cellular defense during the acute inflammatory response. They rapidly migrate to infection sites,
where they phagocytose pathogens and debris.
5. Which of the following hypersensitivity reactions is mediated by IgE antibodies and is responsible for
anaphylaxis?
A) Type I hypersensitivity
B) Type II hypersensitivity
C) Type III hypersensitivity
D) Type IV hypersensitivity
, Correct Answer: Type I hypersensitivity
Rationale: Type I hypersensitivity reactions are IgE-mediated and are responsible for anaphylaxis,
allergic rhinitis, and asthma. Type II reactions are antibody-mediated (IgG/IgM), Type III are immune-
complex mediated, and Type IV are T-cell mediated (delayed-type hypersensitivity).
6. Autoimmune disorders present significant diagnostic challenges primarily because:
A) They always present with the same symptoms in every patient
B) There is a single definitive test for all autoimmune diseases
C) Over 80 distinct autoimmune diseases exist with overlapping, nonspecific symptoms
D) Serological markers are 100% specific and sensitive
Correct Answer: Over 80 distinct autoimmune diseases exist with overlapping, nonspecific symptoms
Rationale: Over 80 distinct autoimmune diseases are recognized, many presenting with nonspecific
symptoms such as fatigue, fever, joint pain, and rashes that overlap with multiple conditions. Serological
markers lack absolute specificity, and there is no single definitive test for most autoimmune diseases.
7. What is the function of antigen-presenting cells (APCs) in the immune response?
A) To directly kill infected cells
B) To process and present antigens to T cells
C) To produce antibodies against pathogens
D) To release histamine during allergic reactions
Correct Answer: To process and present antigens to T cells
Rationale: Antigen-presenting cells (APCs) process antigens and present them on their surface via MHC
molecules to T cells. This is essential for initiating adaptive immune responses. B cells produce
antibodies, cytotoxic T cells kill infected cells, and mast cells release histamine.
