, Question 1
Which of the following best explains why a patient with a mutation causing
loss of function in the Na+/K+ ATPase pump in neurons would exhibit altered
resting membrane potential and impaired action potential propagation?
A. The pump directly generates the action potential by exporting Na+
ions.
B. The pump maintains the concentration gradients of Na+ and K+
necessary for the resting potential and excitability.
C. The pump is responsible for neurotransmitter release at the synapse.
D. The pump regulates intracellular calcium levels, affecting muscle
contraction.
Correct Answer: B - The pump maintains the concentration
gradients of Na+ and K+ necessary for the resting potential and
excitability.
RATIONALE
The Na+/K+ ATPase maintains the electrochemical gradients of Na+
and K+ across the membrane, which are essential for the resting
membrane potential and action potential generation. Loss of function
would dissipate these gradients, reducing excitability. Other options
misattribute roles to the pump.
Question 2
A researcher observes that a specific tissue exhibits high tensile strength,
resists stretch, and contains abundant collagen fibers arranged in parallel
bundles with fibroblasts scattered between them. Which tissue type is this?
A. Elastic connective tissue
B. Dense regular connective tissue
C. Reticular connective tissue
D. Hyaline cartilage
Correct Answer: B - Dense regular connective tissue
Page 2
, RATIONALE
Dense regular connective tissue features parallel collagen bundles that
provide tensile strength and resistance to stretch in one direction, as
found in tendons and ligaments. Elastic tissue contains elastic fibers,
reticular tissue has a network of reticular fibers, and hyaline cartilage
has a glassy matrix with chondrocytes.
Question 3
In a patient with hyperparathyroidism, which of the following bone cell
activities would be primarily increased, leading to elevated blood calcium
levels?
A. Osteoblast activity
B. Osteoclast activity
C. Osteocyte activity
D. Chondrocyte activity
Correct Answer: B - Osteoclast activity
RATIONALE
Parathyroid hormone stimulates osteoclasts to resorb bone, releasing
calcium into the blood. Osteoblasts build bone, osteocytes maintain
bone, and chondrocytes form cartilage, none of which directly elevate
blood calcium in this context.
Question 4
During a muscle contraction, which of the following events directly requires
ATP hydrolysis?
A. Release of calcium from the sarcoplasmic reticulum
B. Binding of acetylcholine to its receptor
C. Power stroke of the myosin head
D. Depolarization of the T-tubule
Correct Answer: C - Power stroke of the myosin head
Page 3
Which of the following best explains why a patient with a mutation causing
loss of function in the Na+/K+ ATPase pump in neurons would exhibit altered
resting membrane potential and impaired action potential propagation?
A. The pump directly generates the action potential by exporting Na+
ions.
B. The pump maintains the concentration gradients of Na+ and K+
necessary for the resting potential and excitability.
C. The pump is responsible for neurotransmitter release at the synapse.
D. The pump regulates intracellular calcium levels, affecting muscle
contraction.
Correct Answer: B - The pump maintains the concentration
gradients of Na+ and K+ necessary for the resting potential and
excitability.
RATIONALE
The Na+/K+ ATPase maintains the electrochemical gradients of Na+
and K+ across the membrane, which are essential for the resting
membrane potential and action potential generation. Loss of function
would dissipate these gradients, reducing excitability. Other options
misattribute roles to the pump.
Question 2
A researcher observes that a specific tissue exhibits high tensile strength,
resists stretch, and contains abundant collagen fibers arranged in parallel
bundles with fibroblasts scattered between them. Which tissue type is this?
A. Elastic connective tissue
B. Dense regular connective tissue
C. Reticular connective tissue
D. Hyaline cartilage
Correct Answer: B - Dense regular connective tissue
Page 2
, RATIONALE
Dense regular connective tissue features parallel collagen bundles that
provide tensile strength and resistance to stretch in one direction, as
found in tendons and ligaments. Elastic tissue contains elastic fibers,
reticular tissue has a network of reticular fibers, and hyaline cartilage
has a glassy matrix with chondrocytes.
Question 3
In a patient with hyperparathyroidism, which of the following bone cell
activities would be primarily increased, leading to elevated blood calcium
levels?
A. Osteoblast activity
B. Osteoclast activity
C. Osteocyte activity
D. Chondrocyte activity
Correct Answer: B - Osteoclast activity
RATIONALE
Parathyroid hormone stimulates osteoclasts to resorb bone, releasing
calcium into the blood. Osteoblasts build bone, osteocytes maintain
bone, and chondrocytes form cartilage, none of which directly elevate
blood calcium in this context.
Question 4
During a muscle contraction, which of the following events directly requires
ATP hydrolysis?
A. Release of calcium from the sarcoplasmic reticulum
B. Binding of acetylcholine to its receptor
C. Power stroke of the myosin head
D. Depolarization of the T-tubule
Correct Answer: C - Power stroke of the myosin head
Page 3
