BIOS 242: EXAM 3 CHAMBERLAIN ACTUAL EXAM
PREP 2026 150 QUESTIONS AND CORRECT
DETAILED ANSWERS ALREADY A GRADED WITH
EXPERT FEEDBACK|NEW AND REVISED
BIOS 242 Exam 3 Practice
PART 1: THE THREE LINES OF DEFENSE
1. The first line of defense is a surface protection composed of _____ and _____
barriers that keep microbes from penetrating sterile body compartments.
A) cellular, chemical
B) anatomical, physiological
C) physical, chemical
D) external, internal
Correct Answer: B) anatomical, physiological
Explanation: The first line of defense consists of anatomical barriers (skin, mucous
membranes) and physiological barriers (temperature, pH, chemical mediators)
that act together to physically prevent microbial entry.
2. Which of the following is NOT a component of the first line of defense?
A) Skin
B) Mucous membranes
,C) Phagocytosis
D) Saliva containing lysozyme
Correct Answer: C) Phagocytosis
Explanation: Phagocytosis is part of the second line of defense (innate immune
cells). The first line includes only physical and chemical barriers: skin, mucous
membranes, tears, saliva, stomach acid, and normal microbiota.
3. The second line of defense is a _____ and _____ system that comes into play if
infectious agents make it past the surface barriers.
A) anatomical, physiological
B) physical, chemical
C) cellular, chemical
D) specific, adaptive
Correct Answer: C) cellular, chemical
Explanation: The second line of defense (innate immunity) involves cellular
components (phagocytes, natural killer cells) and chemical components
(complement proteins, interferons, antimicrobial peptides) that act rapidly and
nonspecifically against invading pathogens.
4. Which type of immunity is present at birth and provides immediate,
nonspecific protection?
A) Adaptive immunity
B) Innate immunity
C) Passive immunity
D) Artificial immunity
Correct Answer: B) Innate immunity
, Explanation: Innate immunity is present at birth, responds immediately, and is
nonspecific. The third line (adaptive immunity) develops after exposure to specific
antigens.
5. What are the two major components of host defenses?
A) Cellular and chemical defenses
B) Innate (nonspecific) and acquired (specific) defenses
C) Physical and physiological defenses
D) Active and passive defenses
Correct Answer: B) Innate (nonspecific) and acquired (specific) defenses
Explanation: Host defenses are divided into innate (nonspecific) and acquired
(specific) defenses. Innate defenses include barriers and rapid responses, while
acquired immunity involves B cells and T cells.
6. Physical barriers on the skin include all of the following EXCEPT:
A) Hair follicles
B) Sweat glands
C) Lysozyme
D) Mucous membranes
Correct Answer: C) Lysozyme
Explanation: Lysozyme is a chemical barrier (an enzyme that breaks down
peptidoglycan), not a physical barrier. Physical barriers include structural
components like skin, hair follicles, sweat glands, and mucous membranes.
7. Which of the following are chemical barriers of the skin? (Select all that apply)
A) Lysozyme
B) Saliva
PREP 2026 150 QUESTIONS AND CORRECT
DETAILED ANSWERS ALREADY A GRADED WITH
EXPERT FEEDBACK|NEW AND REVISED
BIOS 242 Exam 3 Practice
PART 1: THE THREE LINES OF DEFENSE
1. The first line of defense is a surface protection composed of _____ and _____
barriers that keep microbes from penetrating sterile body compartments.
A) cellular, chemical
B) anatomical, physiological
C) physical, chemical
D) external, internal
Correct Answer: B) anatomical, physiological
Explanation: The first line of defense consists of anatomical barriers (skin, mucous
membranes) and physiological barriers (temperature, pH, chemical mediators)
that act together to physically prevent microbial entry.
2. Which of the following is NOT a component of the first line of defense?
A) Skin
B) Mucous membranes
,C) Phagocytosis
D) Saliva containing lysozyme
Correct Answer: C) Phagocytosis
Explanation: Phagocytosis is part of the second line of defense (innate immune
cells). The first line includes only physical and chemical barriers: skin, mucous
membranes, tears, saliva, stomach acid, and normal microbiota.
3. The second line of defense is a _____ and _____ system that comes into play if
infectious agents make it past the surface barriers.
A) anatomical, physiological
B) physical, chemical
C) cellular, chemical
D) specific, adaptive
Correct Answer: C) cellular, chemical
Explanation: The second line of defense (innate immunity) involves cellular
components (phagocytes, natural killer cells) and chemical components
(complement proteins, interferons, antimicrobial peptides) that act rapidly and
nonspecifically against invading pathogens.
4. Which type of immunity is present at birth and provides immediate,
nonspecific protection?
A) Adaptive immunity
B) Innate immunity
C) Passive immunity
D) Artificial immunity
Correct Answer: B) Innate immunity
, Explanation: Innate immunity is present at birth, responds immediately, and is
nonspecific. The third line (adaptive immunity) develops after exposure to specific
antigens.
5. What are the two major components of host defenses?
A) Cellular and chemical defenses
B) Innate (nonspecific) and acquired (specific) defenses
C) Physical and physiological defenses
D) Active and passive defenses
Correct Answer: B) Innate (nonspecific) and acquired (specific) defenses
Explanation: Host defenses are divided into innate (nonspecific) and acquired
(specific) defenses. Innate defenses include barriers and rapid responses, while
acquired immunity involves B cells and T cells.
6. Physical barriers on the skin include all of the following EXCEPT:
A) Hair follicles
B) Sweat glands
C) Lysozyme
D) Mucous membranes
Correct Answer: C) Lysozyme
Explanation: Lysozyme is a chemical barrier (an enzyme that breaks down
peptidoglycan), not a physical barrier. Physical barriers include structural
components like skin, hair follicles, sweat glands, and mucous membranes.
7. Which of the following are chemical barriers of the skin? (Select all that apply)
A) Lysozyme
B) Saliva
