PCB 3703 Exam 1 V3 | PCB 3703 Human
Physiology | Actual Q&A with Rationale (PCB3703
Exam 1) | University of Central Florida
1. Which component of a homeostatic control system is responsible for detecting a change in
a regulated variable?
A. Effector
B. Integrating center
C. Sensor (Receptor)
D. Set point
Correct Answer: C
Explanation: The sensor or receptor is the specific component that monitors the
environment and responds to stimuli by sending data to the control center. This represents
the first step in the feedback loop process. Without a functional sensor, the body cannot
initiate a response to deviations from homeostasis.
2. In a negative feedback loop, what is the primary role of the effector?
A. To compare the input with a set point
B. To produce a response that opposes the original change
C. To detect the initial stimulus
D. To amplify the deviation from the set point
,Correct Answer: B
Explanation: The effector receives signals from the integrating center and carries out a
response to restore the variable to its normal range. This response acts to negate or
reverse the direction of the initial stimulus. Most physiological systems in the human body
rely on this mechanism to maintain stability.
3. Which of the following is an example of a positive feedback mechanism?
A. Regulation of blood glucose levels
B. Maintenance of body temperature
C. The process of blood clotting
D. Control of blood pressure
Correct Answer: C
Explanation: Positive feedback loops act to reinforce or amplify a change rather than
reversing it. Blood clotting and childbirth are classic examples where the response
continues until a definitive endpoint is achieved. This type of feedback is less common in
physiological regulation compared to negative feedback.
4. Which fluid compartment contains the largest percentage of total body water?
A. Plasma
B. Interstitial fluid
C. Intracellular fluid (ICF)
, D. Extracellular fluid (ECF)
Correct Answer: C
Explanation: The intracellular fluid (ICF) resides inside the trillions of cells in the body
and accounts for approximately two-thirds of total body water. The remaining one-third is
found in the extracellular fluid, which includes plasma and interstitial fluid. Maintaining the
balance between these compartments is vital for cellular function and pressure.
5. The plasma membrane is described as ‘amphipathic’ because it contains:
A. Only hydrophobic proteins
B. Only polar carbohydrate chains
C. Both hydrophilic and hydrophobic regions
D. Exclusively non-polar fatty acids
Correct Answer: C
Explanation: Phospholipids have a polar, hydrophilic head and two non-polar,
hydrophobic tails. This dual nature allows them to form a bilayer that serves as a selective
barrier for the cell. The amphipathic property is essential for the structural integrity and
permeability of all biological membranes.
6. What is the function of cholesterol within the cell membrane?
A. To stabilize the membrane and regulate fluidity
B. To facilitate protein synthesis
Physiology | Actual Q&A with Rationale (PCB3703
Exam 1) | University of Central Florida
1. Which component of a homeostatic control system is responsible for detecting a change in
a regulated variable?
A. Effector
B. Integrating center
C. Sensor (Receptor)
D. Set point
Correct Answer: C
Explanation: The sensor or receptor is the specific component that monitors the
environment and responds to stimuli by sending data to the control center. This represents
the first step in the feedback loop process. Without a functional sensor, the body cannot
initiate a response to deviations from homeostasis.
2. In a negative feedback loop, what is the primary role of the effector?
A. To compare the input with a set point
B. To produce a response that opposes the original change
C. To detect the initial stimulus
D. To amplify the deviation from the set point
,Correct Answer: B
Explanation: The effector receives signals from the integrating center and carries out a
response to restore the variable to its normal range. This response acts to negate or
reverse the direction of the initial stimulus. Most physiological systems in the human body
rely on this mechanism to maintain stability.
3. Which of the following is an example of a positive feedback mechanism?
A. Regulation of blood glucose levels
B. Maintenance of body temperature
C. The process of blood clotting
D. Control of blood pressure
Correct Answer: C
Explanation: Positive feedback loops act to reinforce or amplify a change rather than
reversing it. Blood clotting and childbirth are classic examples where the response
continues until a definitive endpoint is achieved. This type of feedback is less common in
physiological regulation compared to negative feedback.
4. Which fluid compartment contains the largest percentage of total body water?
A. Plasma
B. Interstitial fluid
C. Intracellular fluid (ICF)
, D. Extracellular fluid (ECF)
Correct Answer: C
Explanation: The intracellular fluid (ICF) resides inside the trillions of cells in the body
and accounts for approximately two-thirds of total body water. The remaining one-third is
found in the extracellular fluid, which includes plasma and interstitial fluid. Maintaining the
balance between these compartments is vital for cellular function and pressure.
5. The plasma membrane is described as ‘amphipathic’ because it contains:
A. Only hydrophobic proteins
B. Only polar carbohydrate chains
C. Both hydrophilic and hydrophobic regions
D. Exclusively non-polar fatty acids
Correct Answer: C
Explanation: Phospholipids have a polar, hydrophilic head and two non-polar,
hydrophobic tails. This dual nature allows them to form a bilayer that serves as a selective
barrier for the cell. The amphipathic property is essential for the structural integrity and
permeability of all biological membranes.
6. What is the function of cholesterol within the cell membrane?
A. To stabilize the membrane and regulate fluidity
B. To facilitate protein synthesis
