UBC BIOL 155 SPRING FINAL EXAM QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED
ANSWERS) | ALREADY GRADED A+ | BRAND NEW
2025/2026 Q&A | Instant Download PDF
Core Domains Covered:
• Innate Immune System: Physical Barriers & First Line of Defense (12 questions)
• Cells of the Immune System & Hematopoiesis (12 questions)
• Innate Immune Response: Phagocytes, Inflammation & Fever (14 questions)
• Complement System: Pathways & Functions (12 questions)
• Lymphatic System: Organs, Tissues & Lymphocytes (10 questions)
• Adaptive Immune System: B Cells & Antibodies (12 questions)
• Adaptive Immune System: T Cells & Cell-Mediated Immunity (12 questions)
• Antigen Presentation & MHC (10 questions)
• Immune Disorders & Hypersensitivity (11 questions)
INNATE IMMUNE SYSTEM: PHYSICAL BARRIERS & FIRST LINE OF DEFENSE
Question 1:
What are examples of physical barriers of the immune system?
A. Antibodies and complement proteins
B. The skin, hair, sweat glands, and mucus layer of the stomach
C. T cells and B cells
D. Cytokines and interleukins
Answer: B. The skin, hair, sweat glands, and mucus layer of the stomach
Rationale: Physical barriers are the first line of defense in the innate immune system.
They include the skin, hair, sweat glands (which produce antimicrobial secretions), and the
mucus layer of the stomach (which traps pathogens and contains acidic secretions).
,Question 2:
Which of the following is NOT considered a physical barrier of the innate immune system?
A. Skin
B. Mucous membranes
C. Antibodies
D. Cilia in the respiratory tract
Answer: C. Antibodies
Rationale: Antibodies are part of the adaptive immune response, not the innate
physical barriers. Physical barriers include skin, mucous membranes, cilia, and secretions
that physically block or trap pathogens.
Question 3:
What is the primary function of the mucus layer in the stomach as a physical barrier?
A. To trap pathogens for elimination
B. To protect the stomach lining and contain acidic secretions that kill pathogens
C. To produce antibodies
D. To activate complement proteins
Answer: B. To protect the stomach lining and contain acidic secretions that kill
pathogens
Rationale: The mucus layer in the stomach protects the gastric epithelium and contains
hydrochloric acid and digestive enzymes that kill many ingested pathogens.
Question 4:
Which of the following is a physical barrier that helps trap pathogens in the respiratory tract?
A. Mucus and cilia
B. Sweat glands
C. Sebaceous glands
D. Keratinized skin
Answer: A. Mucus and cilia
, Rationale: The respiratory tract is lined with mucus-producing goblet cells and ciliated
epithelial cells. Mucus traps pathogens and particles, while cilia sweep the mucus upward
for expulsion.
Question 5:
The skin acts as a physical barrier due to which of the following properties?
A. Presence of antibodies
B. Keratinized stratified squamous epithelium
C. Presence of T cells
D. Production of complement proteins
Answer: B. Keratinized stratified squamous epithelium
Rationale: The skin is composed of keratinized stratified squamous epithelium, which
provides a tough, impermeable barrier that prevents pathogen entry.
Question 6:
Which of the following secretions contain antimicrobial substances such as lysozyme?
A. Tears and saliva
B. Stomach acid
C. Bile
D. Pancreatic juice
Answer: A. Tears and saliva
Rationale: Tears and saliva contain lysozyme, an enzyme that breaks down bacterial
cell walls, providing antimicrobial protection.
Question 7:
What is the role of hair in the innate immune system?
A. Production of antibodies
B. Trapping pathogens and preventing entry
C. Activation of complement
D. Phagocytosis of bacteria
, Answer: B. Trapping pathogens and preventing entry
Rationale: Hair in the nasal passages and other areas traps pathogens and particles,
preventing them from entering the body.
Question 8:
What is the common origin for all white blood cells?
A. Liver
B. Bone marrow
C. Thymus
D. Spleen
Answer: B. Bone marrow
Rationale: All white blood cells (leukocytes) originate from hematopoietic stem cells in
the bone marrow. They differentiate into various cell types including lymphocytes,
monocytes, and granulocytes.
Question 9:
Which of the following is a component of the first line of defense?
A. Skin
B. Neutrophils
C. Complement proteins
D. Antibodies
Answer: A. Skin
Rationale: The first line of defense consists of physical and chemical barriers, including
the skin, mucous membranes, and secretions.
Question 10:
Which of the following is NOT a component of the innate immune system?
A. Skin
B. Phagocytes
CORRECT DETAILED ANSWERS (VERIFIED
ANSWERS) | ALREADY GRADED A+ | BRAND NEW
2025/2026 Q&A | Instant Download PDF
Core Domains Covered:
• Innate Immune System: Physical Barriers & First Line of Defense (12 questions)
• Cells of the Immune System & Hematopoiesis (12 questions)
• Innate Immune Response: Phagocytes, Inflammation & Fever (14 questions)
• Complement System: Pathways & Functions (12 questions)
• Lymphatic System: Organs, Tissues & Lymphocytes (10 questions)
• Adaptive Immune System: B Cells & Antibodies (12 questions)
• Adaptive Immune System: T Cells & Cell-Mediated Immunity (12 questions)
• Antigen Presentation & MHC (10 questions)
• Immune Disorders & Hypersensitivity (11 questions)
INNATE IMMUNE SYSTEM: PHYSICAL BARRIERS & FIRST LINE OF DEFENSE
Question 1:
What are examples of physical barriers of the immune system?
A. Antibodies and complement proteins
B. The skin, hair, sweat glands, and mucus layer of the stomach
C. T cells and B cells
D. Cytokines and interleukins
Answer: B. The skin, hair, sweat glands, and mucus layer of the stomach
Rationale: Physical barriers are the first line of defense in the innate immune system.
They include the skin, hair, sweat glands (which produce antimicrobial secretions), and the
mucus layer of the stomach (which traps pathogens and contains acidic secretions).
,Question 2:
Which of the following is NOT considered a physical barrier of the innate immune system?
A. Skin
B. Mucous membranes
C. Antibodies
D. Cilia in the respiratory tract
Answer: C. Antibodies
Rationale: Antibodies are part of the adaptive immune response, not the innate
physical barriers. Physical barriers include skin, mucous membranes, cilia, and secretions
that physically block or trap pathogens.
Question 3:
What is the primary function of the mucus layer in the stomach as a physical barrier?
A. To trap pathogens for elimination
B. To protect the stomach lining and contain acidic secretions that kill pathogens
C. To produce antibodies
D. To activate complement proteins
Answer: B. To protect the stomach lining and contain acidic secretions that kill
pathogens
Rationale: The mucus layer in the stomach protects the gastric epithelium and contains
hydrochloric acid and digestive enzymes that kill many ingested pathogens.
Question 4:
Which of the following is a physical barrier that helps trap pathogens in the respiratory tract?
A. Mucus and cilia
B. Sweat glands
C. Sebaceous glands
D. Keratinized skin
Answer: A. Mucus and cilia
, Rationale: The respiratory tract is lined with mucus-producing goblet cells and ciliated
epithelial cells. Mucus traps pathogens and particles, while cilia sweep the mucus upward
for expulsion.
Question 5:
The skin acts as a physical barrier due to which of the following properties?
A. Presence of antibodies
B. Keratinized stratified squamous epithelium
C. Presence of T cells
D. Production of complement proteins
Answer: B. Keratinized stratified squamous epithelium
Rationale: The skin is composed of keratinized stratified squamous epithelium, which
provides a tough, impermeable barrier that prevents pathogen entry.
Question 6:
Which of the following secretions contain antimicrobial substances such as lysozyme?
A. Tears and saliva
B. Stomach acid
C. Bile
D. Pancreatic juice
Answer: A. Tears and saliva
Rationale: Tears and saliva contain lysozyme, an enzyme that breaks down bacterial
cell walls, providing antimicrobial protection.
Question 7:
What is the role of hair in the innate immune system?
A. Production of antibodies
B. Trapping pathogens and preventing entry
C. Activation of complement
D. Phagocytosis of bacteria
, Answer: B. Trapping pathogens and preventing entry
Rationale: Hair in the nasal passages and other areas traps pathogens and particles,
preventing them from entering the body.
Question 8:
What is the common origin for all white blood cells?
A. Liver
B. Bone marrow
C. Thymus
D. Spleen
Answer: B. Bone marrow
Rationale: All white blood cells (leukocytes) originate from hematopoietic stem cells in
the bone marrow. They differentiate into various cell types including lymphocytes,
monocytes, and granulocytes.
Question 9:
Which of the following is a component of the first line of defense?
A. Skin
B. Neutrophils
C. Complement proteins
D. Antibodies
Answer: A. Skin
Rationale: The first line of defense consists of physical and chemical barriers, including
the skin, mucous membranes, and secretions.
Question 10:
Which of the following is NOT a component of the innate immune system?
A. Skin
B. Phagocytes
