,Portage Learning CHEM 103 General Chemistry I Module 8
Exam | 2025 Updated Edition with 100% Verified Answers
Question 1
Which of the following cellular components contains a specialized lipid bilayer
membrane and is filled with hydrolytic enzymes optimized for intracellular digestion?
A) Ribosome
B) Nucleolus
C) Lysosome
D) Centrosome
Answer: C) Lysosome
Rationale: Lysosomes are membrane-bound organelles that contain acid hydrolases.
They fuse with endocytic vesicles to break down macromolecules, worn-out organelles,
and engulfed pathogens.
Question 2
A patient presents with extreme muscle weakness. Clinical testing reveals a genetic
mutation that causes an overproduction of acetylcholinesterase within the
neuromuscular junction. Which of the following effects will this mutation have on
synaptic transmission?
A) Acetylcholine will remain bound to receptors indefinitely.
B) Muscle fibers will undergo continuous, uninhibited tetanic contractions.
C) Acetylcholine will be broken down prematurely, preventing the muscle from reaching
threshold.
D) Voltage-gated calcium channels on the presynaptic terminal will lock open.
Answer: C) Acetylcholine will be broken down prematurely, preventing the
muscle from reaching threshold.
Rationale: Acetylcholinesterase rapidly degrades acetylcholine in the synaptic cleft. An
overproduction of this enzyme clears the neurotransmitter before it can adequately bind
to nicotinic receptors and trigger an action potential.
Question 3
Which epidermal layer features keratinocytes that have ceased dividing and have begun
accumulating dense keratohyalin granules, giving the cytoplasm a distinct speckled
appearance?
A) Stratum basale
B) Stratum spinosum
C) Stratum granulosum
D) Stratum corneum
, Answer: C) Stratum granulosum
Rationale: The stratum granulosum (granular layer) consists of 3–5 layers of
keratinocytes undergoing apoptosis. They display dark-staining keratohyalin granules
that organize keratin filaments, along with lamellar granules that secrete a water-
resistant glycolipid.
Question 4
During structural endochondral ossification, which specific event marks the
transformation of the perichondrium into a bone-depositing periosteum?
A) Chondrocytes secrete alkaline phosphatase to dissolve the articular cartilage.
B) Blood vessels infiltrate the perichondrium, stimulating osteoprogenitor cells to
differentiate into osteoblasts.
C) Fibrocartilage chondrocytes undergo rapid mitosis to close the medullary cavity.
D) Hydroxyapatite crystals precipitate directly into the fibrous cartilage matrix.
Answer: B) Blood vessels infiltrate the perichondrium, stimulating
osteoprogenitor cells to differentiate into osteoblasts.
Rationale: Endochondral ossification requires a vascular trigger. Infiltration of blood
vessels into the surrounding perichondrium changes the nutrient profile, signaling
localized cells to differentiate into osteoblasts, which form the periosteal bone collar.
Question 5
What functional classification is assigned to a slightly movable joint where the
articulating bone surfaces are connected by a band of dense regular collagenous tissue,
such as an interosseous membrane?
A) Synarthrosis
B) Amphiarthrosis
C) Diarthrosis
D) Synchondrosis
Answer: B) Amphiarthrosis
Rationale: Joints are functionally categorized by mobility: synarthroses are completely
immovable, amphiarthroses are slightly movable, and diarthroses are freely movable.
Structural syndesmoses (interosseous membranes) function as amphiarthroses.
Question 6
During the relaxation phase of a skeletal muscle fiber, what active transport mechanism
is responsible for moving calcium ions back into the terminal cisternae of the
sarcoplasmic reticulum?
A) Sodium-potassium ATPase pump
B) SERCA (Sarcoplasmic/Endoplasmic Reticulum Calcium ATPase) pump
Exam | 2025 Updated Edition with 100% Verified Answers
Question 1
Which of the following cellular components contains a specialized lipid bilayer
membrane and is filled with hydrolytic enzymes optimized for intracellular digestion?
A) Ribosome
B) Nucleolus
C) Lysosome
D) Centrosome
Answer: C) Lysosome
Rationale: Lysosomes are membrane-bound organelles that contain acid hydrolases.
They fuse with endocytic vesicles to break down macromolecules, worn-out organelles,
and engulfed pathogens.
Question 2
A patient presents with extreme muscle weakness. Clinical testing reveals a genetic
mutation that causes an overproduction of acetylcholinesterase within the
neuromuscular junction. Which of the following effects will this mutation have on
synaptic transmission?
A) Acetylcholine will remain bound to receptors indefinitely.
B) Muscle fibers will undergo continuous, uninhibited tetanic contractions.
C) Acetylcholine will be broken down prematurely, preventing the muscle from reaching
threshold.
D) Voltage-gated calcium channels on the presynaptic terminal will lock open.
Answer: C) Acetylcholine will be broken down prematurely, preventing the
muscle from reaching threshold.
Rationale: Acetylcholinesterase rapidly degrades acetylcholine in the synaptic cleft. An
overproduction of this enzyme clears the neurotransmitter before it can adequately bind
to nicotinic receptors and trigger an action potential.
Question 3
Which epidermal layer features keratinocytes that have ceased dividing and have begun
accumulating dense keratohyalin granules, giving the cytoplasm a distinct speckled
appearance?
A) Stratum basale
B) Stratum spinosum
C) Stratum granulosum
D) Stratum corneum
, Answer: C) Stratum granulosum
Rationale: The stratum granulosum (granular layer) consists of 3–5 layers of
keratinocytes undergoing apoptosis. They display dark-staining keratohyalin granules
that organize keratin filaments, along with lamellar granules that secrete a water-
resistant glycolipid.
Question 4
During structural endochondral ossification, which specific event marks the
transformation of the perichondrium into a bone-depositing periosteum?
A) Chondrocytes secrete alkaline phosphatase to dissolve the articular cartilage.
B) Blood vessels infiltrate the perichondrium, stimulating osteoprogenitor cells to
differentiate into osteoblasts.
C) Fibrocartilage chondrocytes undergo rapid mitosis to close the medullary cavity.
D) Hydroxyapatite crystals precipitate directly into the fibrous cartilage matrix.
Answer: B) Blood vessels infiltrate the perichondrium, stimulating
osteoprogenitor cells to differentiate into osteoblasts.
Rationale: Endochondral ossification requires a vascular trigger. Infiltration of blood
vessels into the surrounding perichondrium changes the nutrient profile, signaling
localized cells to differentiate into osteoblasts, which form the periosteal bone collar.
Question 5
What functional classification is assigned to a slightly movable joint where the
articulating bone surfaces are connected by a band of dense regular collagenous tissue,
such as an interosseous membrane?
A) Synarthrosis
B) Amphiarthrosis
C) Diarthrosis
D) Synchondrosis
Answer: B) Amphiarthrosis
Rationale: Joints are functionally categorized by mobility: synarthroses are completely
immovable, amphiarthroses are slightly movable, and diarthroses are freely movable.
Structural syndesmoses (interosseous membranes) function as amphiarthroses.
Question 6
During the relaxation phase of a skeletal muscle fiber, what active transport mechanism
is responsible for moving calcium ions back into the terminal cisternae of the
sarcoplasmic reticulum?
A) Sodium-potassium ATPase pump
B) SERCA (Sarcoplasmic/Endoplasmic Reticulum Calcium ATPase) pump
