SCI 221 Exam 1 V3 | SCI 221 Human
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 1) | Nightingale
College
1. Which component of a homeostatic control system is responsible for detecting changes in
the internal environment?
A. Receptor
B. Control Center
C. Effector
D. Output pathway
Correct Answer: A
Rationale: The receptor is the specific component that monitors environment changes and
responds to stimuli. It sends information to the control center via the afferent pathway.
Without functional receptors, the body cannot initiate the necessary feedback loops to
maintain homeostasis.
2. In a negative feedback loop, what is the primary role of the effector?
A. To process the signal and determine the set point
B. To carry out a response that opposes the initial stimulus
,C. To amplify the stimulus until a climax is reached
D. To detect the initial change in variable
Correct Answer: B
Rationale: The effector receives output from the control center and produces a response.
In negative feedback, this response works to reduce or shut off the original stimulus. This
mechanism ensures that the internal environment returns to its ideal physiological set
point.
3. Which of the following processes requires the direct use of ATP to move substances against
their concentration gradient?
A. Primary active transport
B. Osmosis
C. Simple diffusion
D. Facilitated diffusion
Correct Answer: A
Rationale: Primary active transport uses energy derived directly from the hydrolysis of
ATP. This process is necessary to move solutes such as ions ‘uphill’ against a concentration
gradient. Examples include the sodium-potassium pump, which is vital for maintaining
cellular membrane potentials.
, 4. What occurs to a red blood cell when it is placed in a hypertonic solution?
A. It will shrink or crenate
B. It will swell and eventually burst (lyse)
C. There will be no net movement of water
D. It will increase its metabolic rate
Correct Answer: A
Rationale: A hypertonic solution has a higher solute concentration than the inside of the
cell. Consequently, water moves out of the cell by osmosis to balance the concentrations.
This loss of water causes the red blood cell to shrivel, a process known as crenation.
5. The resting membrane potential of a typical neuron is primarily maintained by which of the
following?
A. Leaky sodium channels only
B. Voltage-gated calcium channels
C. The sodium-potassium pump and leak channels
D. Chemically gated chloride channels
Correct Answer: C
Rationale: The resting membrane potential is established by the unequal distribution of
ions across the plasma membrane. The sodium-potassium pump moves three sodium ions
Physiology with Intervention Skill-Based
(ISB) Experiential Learning | Q&A with
Rationale (SCI221 Exam 1) | Nightingale
College
1. Which component of a homeostatic control system is responsible for detecting changes in
the internal environment?
A. Receptor
B. Control Center
C. Effector
D. Output pathway
Correct Answer: A
Rationale: The receptor is the specific component that monitors environment changes and
responds to stimuli. It sends information to the control center via the afferent pathway.
Without functional receptors, the body cannot initiate the necessary feedback loops to
maintain homeostasis.
2. In a negative feedback loop, what is the primary role of the effector?
A. To process the signal and determine the set point
B. To carry out a response that opposes the initial stimulus
,C. To amplify the stimulus until a climax is reached
D. To detect the initial change in variable
Correct Answer: B
Rationale: The effector receives output from the control center and produces a response.
In negative feedback, this response works to reduce or shut off the original stimulus. This
mechanism ensures that the internal environment returns to its ideal physiological set
point.
3. Which of the following processes requires the direct use of ATP to move substances against
their concentration gradient?
A. Primary active transport
B. Osmosis
C. Simple diffusion
D. Facilitated diffusion
Correct Answer: A
Rationale: Primary active transport uses energy derived directly from the hydrolysis of
ATP. This process is necessary to move solutes such as ions ‘uphill’ against a concentration
gradient. Examples include the sodium-potassium pump, which is vital for maintaining
cellular membrane potentials.
, 4. What occurs to a red blood cell when it is placed in a hypertonic solution?
A. It will shrink or crenate
B. It will swell and eventually burst (lyse)
C. There will be no net movement of water
D. It will increase its metabolic rate
Correct Answer: A
Rationale: A hypertonic solution has a higher solute concentration than the inside of the
cell. Consequently, water moves out of the cell by osmosis to balance the concentrations.
This loss of water causes the red blood cell to shrivel, a process known as crenation.
5. The resting membrane potential of a typical neuron is primarily maintained by which of the
following?
A. Leaky sodium channels only
B. Voltage-gated calcium channels
C. The sodium-potassium pump and leak channels
D. Chemically gated chloride channels
Correct Answer: C
Rationale: The resting membrane potential is established by the unequal distribution of
ions across the plasma membrane. The sodium-potassium pump moves three sodium ions
