,BIOL 102 Module 4 | Essential Biology II w/Lab
Exam Q&A | Portage Learning
1. Homeostasis is best defined as the maintenance of:
A) A constant external environment
B) Equilibrium around set points within the internal environment
C) Continuous cellular division
D) Maximum metabolic rate at all times
Correct Answer: Equilibrium around set points within the internal environment
Rationale: Homeostasis maintains internal variables—such as temperature, pH,
and blood glucose—near set points or standard ranges despite external changes. It
does not mean keeping the external environment constant, nor does it refer to cell
division or maximizing metabolism.
2. Which component of a homeostatic control system detects a change in the
internal environment?
A) Effector
B) Integrating center
C) Sensor or receptor
D) Set point
Correct Answer: Sensor or receptor
,Rationale: The sensor (receptor) monitors a variable and detects deviations
from the set point. The integrating center processes the signal, and the effector
produces the response that restores balance.
3. In a negative feedback loop, the response to a deviation:
A) Amplifies the deviation
B) Opposes or reverses the deviation
C) Has no effect on the deviation
D) Permanently resets the set point
Correct Answer: Opposes or reverses the deviation
Rationale: Negative feedback counteracts the initial change, bringing the
variable back toward its set point. Positive feedback, by contrast, amplifies the
deviation and is far less common in routine homeostatic regulation.
4. Which of the following is the primary integrating center for most homeostatic
reflexes?
A) Cerebellum
B) Hypothalamus
C) Medulla oblongata only
D) Thyroid gland
Correct Answer: Hypothalamus
Rationale: The hypothalamus contains nuclei that sense and integrate signals
for temperature, osmolarity, and endocrine regulation, making it a central
, homeostatic control center. The cerebellum coordinates movement, and the
thyroid gland is an effector.
5. Which sequence correctly represents a homeostatic control pathway?
A) Effector → sensor → integrating center → response
B) Set point → effector → sensor → integrating center
C) Stimulus → sensor → integrating center → effector → response
D) Integrating center → stimulus → effector → sensor
Correct Answer: Stimulus → sensor → integrating center → effector →
response
Rationale: A stimulus is detected by a sensor, relayed to an integrating center,
and the center activates an effector whose response restores the variable. This
sequence is the standard reflex arc for homeostatic control.
6. Blood clotting and uterine contractions during childbirth are examples of:
A) Negative feedback
B) Positive feedback
C) Feed-forward inhibition
D) Set-point resetting
Correct Answer: Positive feedback
Rationale: In both clotting and childbirth, the initial response amplifies the
stimulus—more clotting factors are activated, and stronger contractions trigger
more oxytocin release—until the process reaches completion.
Exam Q&A | Portage Learning
1. Homeostasis is best defined as the maintenance of:
A) A constant external environment
B) Equilibrium around set points within the internal environment
C) Continuous cellular division
D) Maximum metabolic rate at all times
Correct Answer: Equilibrium around set points within the internal environment
Rationale: Homeostasis maintains internal variables—such as temperature, pH,
and blood glucose—near set points or standard ranges despite external changes. It
does not mean keeping the external environment constant, nor does it refer to cell
division or maximizing metabolism.
2. Which component of a homeostatic control system detects a change in the
internal environment?
A) Effector
B) Integrating center
C) Sensor or receptor
D) Set point
Correct Answer: Sensor or receptor
,Rationale: The sensor (receptor) monitors a variable and detects deviations
from the set point. The integrating center processes the signal, and the effector
produces the response that restores balance.
3. In a negative feedback loop, the response to a deviation:
A) Amplifies the deviation
B) Opposes or reverses the deviation
C) Has no effect on the deviation
D) Permanently resets the set point
Correct Answer: Opposes or reverses the deviation
Rationale: Negative feedback counteracts the initial change, bringing the
variable back toward its set point. Positive feedback, by contrast, amplifies the
deviation and is far less common in routine homeostatic regulation.
4. Which of the following is the primary integrating center for most homeostatic
reflexes?
A) Cerebellum
B) Hypothalamus
C) Medulla oblongata only
D) Thyroid gland
Correct Answer: Hypothalamus
Rationale: The hypothalamus contains nuclei that sense and integrate signals
for temperature, osmolarity, and endocrine regulation, making it a central
, homeostatic control center. The cerebellum coordinates movement, and the
thyroid gland is an effector.
5. Which sequence correctly represents a homeostatic control pathway?
A) Effector → sensor → integrating center → response
B) Set point → effector → sensor → integrating center
C) Stimulus → sensor → integrating center → effector → response
D) Integrating center → stimulus → effector → sensor
Correct Answer: Stimulus → sensor → integrating center → effector →
response
Rationale: A stimulus is detected by a sensor, relayed to an integrating center,
and the center activates an effector whose response restores the variable. This
sequence is the standard reflex arc for homeostatic control.
6. Blood clotting and uterine contractions during childbirth are examples of:
A) Negative feedback
B) Positive feedback
C) Feed-forward inhibition
D) Set-point resetting
Correct Answer: Positive feedback
Rationale: In both clotting and childbirth, the initial response amplifies the
stimulus—more clotting factors are activated, and stronger contractions trigger
more oxytocin release—until the process reaches completion.
