WGU D312 Anatomy and Physiology I
Objective Assessment Exam
2026/2027 Newly Released
70 Verified Questions with answers and exper t rationales
Q1: Which organelle is responsible for synthesizing lipids, detoxifying drugs and alcohol, and
storing calcium ions in skeletal muscle cells?
A. Lysosome
B. Golgi apparatus
C. Smooth endoplasmic reticulum
D. Rough endoplasmic reticulum
Correct Answer: C
Rationale: Correct because the smooth endoplasmic reticulum (SER) functions in lipid synthesis,
steroid hormone production, carbohydrate metabolism, and detoxification of drugs and
poisons. Additionally, in muscle cells, the SER plays a critical role in sequestering calcium ions for
muscle contraction.
Q2: A cell is placed in a hypertonic solution. Which of the following events describes the
movement of water?
A. Water moves into the cell, causing it to swell and potentially lyse.
B. Water moves out of the cell, causing it to shrink (crenate).
C. Water moves in and out of the cell equally, maintaining equilibrium.
D. No movement of water occurs across the membrane.
Correct Answer: B
Rationale: Correct because a hypertonic solution has a higher solute concentration than the
intracellular fluid; therefore, water moves out of the cell via osmosis to equalize the solute
,concentration. This loss of water causes the cell to shrink, a process known as crenation in
animal cells.
Q3: During which phase of the cell cycle does DNA replication occur?
A. G1 phase
B. S phase
C. G2 phase
D. M phase
Correct Answer: B
Rationale: Correct because the S phase (Synthesis phase) is the portion of interphase in which
DNA is replicated, ensuring that each daughter cell receives an exact copy of the genome. This
phase occurs between the G1 phase (cell growth) and the G2 phase (preparation for mitosis).
Q4: Which tissue type consists of a single layer of flattened cells and is found lining the air sacs
of the lungs and the inner lining of blood vessels?
A. Simple cuboidal epithelium
B. Stratified squamous epithelium
C. Simple columnar epithelium
D. Simple squamous epithelium
Correct Answer: D
Rationale: Correct because simple squamous epithelium is composed of a single layer of thin,
flat cells, which facilitates rapid diffusion and filtration. Its location in the alveoli (gas exchange)
and blood vessels (endothelium) is ideal for minimizing the barrier to transport.
Q5: Which type of connective tissue fiber provides the tissue with the ability to return to its
original shape after being stretched?
A. Collagen fibers
B. Elastic fibers
C. Reticular fibers
D. Muscle fibers
, Correct Answer: B
Rationale: Correct because elastic fibers are composed of the protein elastin, which allows
them to stretch significantly and then recoil back to their original length without deformation.
These fibers are abundant in structures that require elasticity, such as the lungs, arteries, and
skin.
Q6: A red, painful, hot, and swollen area is observed at a site of injury. Which of the following
cells is most likely responsible for releasing histamine to initiate this inflammatory response?
A. Fibroblast
B. Mast cell
C. Osteoblast
D. Chondrocyte
Correct Answer: B
Rationale: Correct because mast cells are granulocytes found in connective tissue that release
histamine and heparin in response to tissue injury or allergens. The release of histamine triggers
vasodilation and increased vascular permeability, causing the classic signs of inflammation.
Q7: Which layer of the epidermis consists of dead, keratinized cells that protect the underlying
layers from abrasion and water loss?
A. Stratum basale
B. Stratum spinosum
C. Stratum granulosum
D. Stratum corneum
Correct Answer: D
Rationale: Correct because the stratum corneum is the outermost layer of the epidermis,
composed of 25 to 30 layers of dead, flattened, anuclear cells filled with keratin. This tough,
protective layer forms the primary barrier against environmental hazards and prevents
excessive water loss.
Objective Assessment Exam
2026/2027 Newly Released
70 Verified Questions with answers and exper t rationales
Q1: Which organelle is responsible for synthesizing lipids, detoxifying drugs and alcohol, and
storing calcium ions in skeletal muscle cells?
A. Lysosome
B. Golgi apparatus
C. Smooth endoplasmic reticulum
D. Rough endoplasmic reticulum
Correct Answer: C
Rationale: Correct because the smooth endoplasmic reticulum (SER) functions in lipid synthesis,
steroid hormone production, carbohydrate metabolism, and detoxification of drugs and
poisons. Additionally, in muscle cells, the SER plays a critical role in sequestering calcium ions for
muscle contraction.
Q2: A cell is placed in a hypertonic solution. Which of the following events describes the
movement of water?
A. Water moves into the cell, causing it to swell and potentially lyse.
B. Water moves out of the cell, causing it to shrink (crenate).
C. Water moves in and out of the cell equally, maintaining equilibrium.
D. No movement of water occurs across the membrane.
Correct Answer: B
Rationale: Correct because a hypertonic solution has a higher solute concentration than the
intracellular fluid; therefore, water moves out of the cell via osmosis to equalize the solute
,concentration. This loss of water causes the cell to shrink, a process known as crenation in
animal cells.
Q3: During which phase of the cell cycle does DNA replication occur?
A. G1 phase
B. S phase
C. G2 phase
D. M phase
Correct Answer: B
Rationale: Correct because the S phase (Synthesis phase) is the portion of interphase in which
DNA is replicated, ensuring that each daughter cell receives an exact copy of the genome. This
phase occurs between the G1 phase (cell growth) and the G2 phase (preparation for mitosis).
Q4: Which tissue type consists of a single layer of flattened cells and is found lining the air sacs
of the lungs and the inner lining of blood vessels?
A. Simple cuboidal epithelium
B. Stratified squamous epithelium
C. Simple columnar epithelium
D. Simple squamous epithelium
Correct Answer: D
Rationale: Correct because simple squamous epithelium is composed of a single layer of thin,
flat cells, which facilitates rapid diffusion and filtration. Its location in the alveoli (gas exchange)
and blood vessels (endothelium) is ideal for minimizing the barrier to transport.
Q5: Which type of connective tissue fiber provides the tissue with the ability to return to its
original shape after being stretched?
A. Collagen fibers
B. Elastic fibers
C. Reticular fibers
D. Muscle fibers
, Correct Answer: B
Rationale: Correct because elastic fibers are composed of the protein elastin, which allows
them to stretch significantly and then recoil back to their original length without deformation.
These fibers are abundant in structures that require elasticity, such as the lungs, arteries, and
skin.
Q6: A red, painful, hot, and swollen area is observed at a site of injury. Which of the following
cells is most likely responsible for releasing histamine to initiate this inflammatory response?
A. Fibroblast
B. Mast cell
C. Osteoblast
D. Chondrocyte
Correct Answer: B
Rationale: Correct because mast cells are granulocytes found in connective tissue that release
histamine and heparin in response to tissue injury or allergens. The release of histamine triggers
vasodilation and increased vascular permeability, causing the classic signs of inflammation.
Q7: Which layer of the epidermis consists of dead, keratinized cells that protect the underlying
layers from abrasion and water loss?
A. Stratum basale
B. Stratum spinosum
C. Stratum granulosum
D. Stratum corneum
Correct Answer: D
Rationale: Correct because the stratum corneum is the outermost layer of the epidermis,
composed of 25 to 30 layers of dead, flattened, anuclear cells filled with keratin. This tough,
protective layer forms the primary barrier against environmental hazards and prevents
excessive water loss.
