BIOL251 HUMAN ANATOMY &
PHYSIOLOGY I
Module 3 Exam Review | 2026/2027
100 Verified Q&A with Detailed Rationales |
A+ Guaranteed
Covering: Integumentary System | Skeletal System | Muscular System
| Introduction to the Nervous System
SECTION 1: THE INTEGUMENTARY SYSTEM
Q1. Which layer of the skin is the outermost and serves as the
primary barrier against the environment?
A. Dermis
B. Hypodermis
C. Epidermis
D. Subcutaneous layer
✔ ANSWER: C. Epidermis
📘 RATIONALE: The epidermis is the outermost layer of the skin and
serves as the primary physical, chemical, and biological barrier. It is
avascular (no blood vessels) and is composed mainly of keratinocytes.
It protects against pathogens, UV radiation, and water loss.
Q2. Which epidermal layer is found ONLY in thick skin (such as
the palms and soles)?
BIOL251 A&P I | Module 3 Exam Review 2025/2026 | 100 Q&A | A+ Guaranteed | Page 1
, A. Stratum spinosum
B. Stratum lucidum
C. Stratum granulosum
D. Stratum basale
✔ ANSWER: B. Stratum lucidum
📘 RATIONALE: The stratum lucidum is a clear, thin layer found only in
thick skin areas such as the palms of the hands and soles of the feet. It
lies between the stratum granulosum and stratum corneum and
consists of dead, flattened keratinocytes filled with eleidin, a precursor
to keratin.
Q3. Which cells in the epidermis produce melanin?
A. Keratinocytes
B. Langerhans cells
C. Merkel cells
D. Melanocytes
✔ ANSWER: D. Melanocytes
📘 RATIONALE: Melanocytes are specialized cells found in the stratum
basale that produce melanin, the pigment responsible for skin, hair,
and eye color. Melanin protects the skin against UV radiation damage.
Keratinocytes absorb the melanin from melanocytes through
phagocytosis.
Q4. The dermis is composed primarily of which type of tissue?
A. Epithelial tissue
B. Dense irregular connective tissue
C. Smooth muscle tissue
D. Areolar connective tissue only
✔ ANSWER: B. Dense irregular connective tissue
📘 RATIONALE: The dermis is composed primarily of dense irregular
connective tissue, particularly in the reticular layer. This gives the skin
BIOL251 A&P I | Module 3 Exam Review 2025/2026 | 100 Q&A | A+ Guaranteed | Page 2
,its strength, elasticity, and flexibility. Collagen fibers provide tensile
strength while elastic fibers allow the skin to stretch and recoil.
Q5. Which layer of the epidermis contains stem cells that
continuously divide to produce new keratinocytes?
A. Stratum corneum
B. Stratum granulosum
C. Stratum basale
D. Stratum spinosum
✔ ANSWER: C. Stratum basale
📘 RATIONALE: The stratum basale (basal layer) is the deepest layer
of the epidermis and contains mitotically active stem cells called basal
cells. These cells continuously divide to produce new keratinocytes
that migrate upward through the other layers. It takes approximately 4-
6 weeks for cells to move from the basale to the surface.
Q6. What is the primary function of the subcutaneous layer
(hypodermis)?
A. Produces new skin cells
B. Provides insulation, energy storage, and anchors skin to
underlying tissue
C. Acts as primary immune barrier
D. Synthesizes vitamin D
✔ ANSWER: B. Provides insulation, energy storage, and anchors
skin to underlying tissue
📘 RATIONALE: The hypodermis (subcutaneous layer) is not
technically part of the skin but lies deep to the dermis. It consists
mainly of adipose tissue and loose connective tissue, providing thermal
insulation, cushioning, energy storage, and anchoring the skin to
underlying muscles and bones.
BIOL251 A&P I | Module 3 Exam Review 2025/2026 | 100 Q&A | A+ Guaranteed | Page 3
, Q7. Vitamin D synthesis in the skin requires exposure to:
A. Infrared radiation
B. Ultraviolet radiation
C. Visible light
D. X-ray radiation
✔ ANSWER: B. Ultraviolet radiation
📘 RATIONALE: UV radiation from sunlight triggers the conversion of
7-dehydrocholesterol in the skin to cholecalciferol (vitamin D3). This is
further converted to active vitamin D (calcitriol) in the liver and kidneys.
Active vitamin D is essential for calcium absorption in the intestines.
Q8. Which type of burn involves destruction of the entire
epidermis and dermis and may affect underlying structures?
A. First-degree (superficial) burn
B. Second-degree (partial thickness) burn
C. Third-degree (full thickness) burn
D. Superficial partial-thickness burn
✔ ANSWER: C. Third-degree (full thickness) burn
📘 RATIONALE: Third-degree (full thickness) burns destroy the entire
epidermis and dermis and may extend into subcutaneous tissue,
muscle, or bone. The area appears white, brown, or black and is
typically painless because nerve endings are destroyed. Skin grafting
is required for healing.
Q9. Hair follicles and sweat glands are derived from which layer
of the skin?
A. Hypodermis
B. Epidermis
C. Dermis
D. Stratum corneum
✔ ANSWER: B. Epidermis
BIOL251 A&P I | Module 3 Exam Review 2025/2026 | 100 Q&A | A+ Guaranteed | Page 4
PHYSIOLOGY I
Module 3 Exam Review | 2026/2027
100 Verified Q&A with Detailed Rationales |
A+ Guaranteed
Covering: Integumentary System | Skeletal System | Muscular System
| Introduction to the Nervous System
SECTION 1: THE INTEGUMENTARY SYSTEM
Q1. Which layer of the skin is the outermost and serves as the
primary barrier against the environment?
A. Dermis
B. Hypodermis
C. Epidermis
D. Subcutaneous layer
✔ ANSWER: C. Epidermis
📘 RATIONALE: The epidermis is the outermost layer of the skin and
serves as the primary physical, chemical, and biological barrier. It is
avascular (no blood vessels) and is composed mainly of keratinocytes.
It protects against pathogens, UV radiation, and water loss.
Q2. Which epidermal layer is found ONLY in thick skin (such as
the palms and soles)?
BIOL251 A&P I | Module 3 Exam Review 2025/2026 | 100 Q&A | A+ Guaranteed | Page 1
, A. Stratum spinosum
B. Stratum lucidum
C. Stratum granulosum
D. Stratum basale
✔ ANSWER: B. Stratum lucidum
📘 RATIONALE: The stratum lucidum is a clear, thin layer found only in
thick skin areas such as the palms of the hands and soles of the feet. It
lies between the stratum granulosum and stratum corneum and
consists of dead, flattened keratinocytes filled with eleidin, a precursor
to keratin.
Q3. Which cells in the epidermis produce melanin?
A. Keratinocytes
B. Langerhans cells
C. Merkel cells
D. Melanocytes
✔ ANSWER: D. Melanocytes
📘 RATIONALE: Melanocytes are specialized cells found in the stratum
basale that produce melanin, the pigment responsible for skin, hair,
and eye color. Melanin protects the skin against UV radiation damage.
Keratinocytes absorb the melanin from melanocytes through
phagocytosis.
Q4. The dermis is composed primarily of which type of tissue?
A. Epithelial tissue
B. Dense irregular connective tissue
C. Smooth muscle tissue
D. Areolar connective tissue only
✔ ANSWER: B. Dense irregular connective tissue
📘 RATIONALE: The dermis is composed primarily of dense irregular
connective tissue, particularly in the reticular layer. This gives the skin
BIOL251 A&P I | Module 3 Exam Review 2025/2026 | 100 Q&A | A+ Guaranteed | Page 2
,its strength, elasticity, and flexibility. Collagen fibers provide tensile
strength while elastic fibers allow the skin to stretch and recoil.
Q5. Which layer of the epidermis contains stem cells that
continuously divide to produce new keratinocytes?
A. Stratum corneum
B. Stratum granulosum
C. Stratum basale
D. Stratum spinosum
✔ ANSWER: C. Stratum basale
📘 RATIONALE: The stratum basale (basal layer) is the deepest layer
of the epidermis and contains mitotically active stem cells called basal
cells. These cells continuously divide to produce new keratinocytes
that migrate upward through the other layers. It takes approximately 4-
6 weeks for cells to move from the basale to the surface.
Q6. What is the primary function of the subcutaneous layer
(hypodermis)?
A. Produces new skin cells
B. Provides insulation, energy storage, and anchors skin to
underlying tissue
C. Acts as primary immune barrier
D. Synthesizes vitamin D
✔ ANSWER: B. Provides insulation, energy storage, and anchors
skin to underlying tissue
📘 RATIONALE: The hypodermis (subcutaneous layer) is not
technically part of the skin but lies deep to the dermis. It consists
mainly of adipose tissue and loose connective tissue, providing thermal
insulation, cushioning, energy storage, and anchoring the skin to
underlying muscles and bones.
BIOL251 A&P I | Module 3 Exam Review 2025/2026 | 100 Q&A | A+ Guaranteed | Page 3
, Q7. Vitamin D synthesis in the skin requires exposure to:
A. Infrared radiation
B. Ultraviolet radiation
C. Visible light
D. X-ray radiation
✔ ANSWER: B. Ultraviolet radiation
📘 RATIONALE: UV radiation from sunlight triggers the conversion of
7-dehydrocholesterol in the skin to cholecalciferol (vitamin D3). This is
further converted to active vitamin D (calcitriol) in the liver and kidneys.
Active vitamin D is essential for calcium absorption in the intestines.
Q8. Which type of burn involves destruction of the entire
epidermis and dermis and may affect underlying structures?
A. First-degree (superficial) burn
B. Second-degree (partial thickness) burn
C. Third-degree (full thickness) burn
D. Superficial partial-thickness burn
✔ ANSWER: C. Third-degree (full thickness) burn
📘 RATIONALE: Third-degree (full thickness) burns destroy the entire
epidermis and dermis and may extend into subcutaneous tissue,
muscle, or bone. The area appears white, brown, or black and is
typically painless because nerve endings are destroyed. Skin grafting
is required for healing.
Q9. Hair follicles and sweat glands are derived from which layer
of the skin?
A. Hypodermis
B. Epidermis
C. Dermis
D. Stratum corneum
✔ ANSWER: B. Epidermis
BIOL251 A&P I | Module 3 Exam Review 2025/2026 | 100 Q&A | A+ Guaranteed | Page 4
