BIOD 102 Biology II Module 4 Exam -
Portage Learning (2026/2027)
Section 1: Principles of Homeostasis & Feedback Loops
Q1: Which of the following best defines the term "homeostasis"?
A. The inability of the body to maintain internal conditions when external conditions change
B. The maintenance of a relatively stable internal environment despite fluctuations in the
external environment
C. A state of unchanging physiological parameters that require no energy expenditure
D. The continuous directional change of internal conditions to match the external environment
Correct Answer: B
Rationale: Homeostasis is the active maintenance of stable internal conditions (like temperature
or pH) regardless of external changes; it is not passive, unchanging, or a matching process.
Q2: A marathon runner's body temperature increases to 39.2°C during a race but returns to 37°C
an hour after finishing. The fact that the body allowed the temperature to rise to 39.2°C without
immediate correction demonstrates which concept?
A. Set point failure
B. Positive feedback
C. Normal range variability
D. Effector fatigue
Correct Answer: C
Rationale: Homeostasis maintains parameters within a normal, safe range around a set point,
allowing temporary deviations like a mild fever or exercise-induced heat before initiating
corrective mechanisms.
.
,Q3: A patient eats a high-carbohydrate meal, causing blood glucose to rise. Pancreatic beta cells
detect this change and release insulin, which stimulates cells to take up glucose, lowering blood
glucose levels. In this scenario, what is the effector?
A. The elevated blood glucose
B. The pancreatic beta cells
C. The body cells that take up glucose
D. The blood vessels supplying the pancreas
Correct Answer: C
Rationale: The effector is the component that carries out the response to restore homeostasis;
here, it is the body cells taking up glucose, while the pancreatic beta cells act as the
sensor/control center.
Q4: What is the primary purpose of a negative feedback loop in human physiology?
A. To amplify a physiological response until an external intervention stops it
B. To continuously increase the production of a specific hormone
C. To reverse a deviation from a set point and restore equilibrium
D. To establish a new, higher baseline for a physiological parameter
Correct Answer: C
Rationale: Negative feedback loops are designed to detect deviations from a set point and
activate effectors to reverse the change, thereby maintaining equilibrium rather than amplifying
it.
Q5: A patient cuts their finger. Platelets adhere to the site and release chemicals that attract more
platelets, rapidly forming a plug. This is an example of:
A. Negative feedback because it stops bleeding
B. Positive feedback because it amplifies the initial platelet accumulation
C. Negative feedback because it prevents excessive blood loss
D. Positive feedback because it lowers blood pressure
Correct Answer: B
.
, Rationale: Blood clotting is a classic positive feedback loop where the initial event (platelet
adhesion) triggers the release of chemicals that enhance further platelet accumulation, amplifying
the response until the clot is formed.
Q6: During labor, the pressure of the baby's head on the cervix stimulates oxytocin release,
which causes stronger uterine contractions. This cycle continues until birth. Why is this
considered positive feedback rather than negative feedback?
A. Because the stimulus (cervical stretch) is amplified rather than reversed by the response
B. Because it involves the endocrine system instead of the nervous system
C. Because the outcome (birth) reverses the initial stimulus
D. Because oxytocin levels decrease immediately after the baby is born
Correct Answer: A
Rationale: Positive feedback amplifies the initial stimulus to drive a process to completion; the
contractions increase cervical stretch, which causes more contractions, rather than reversing the
stretch as negative feedback would.
Q7: A patient experiences a massive hemorrhage, causing blood pressure to drop so severely that
the heart cannot pump effectively, leading to further drops in blood pressure and cardiac output.
This deteriorating cycle is best described as:
A. Homeostatic compensation
B. A negative feedback loop restoring blood volume
C. A positive feedback loop creating a vicious cycle
D. An effector successfully opposing the stimulus
Correct Answer: C
Rationale: A vicious cycle occurs when a stimulus triggers a response that further exacerbates
the initial problem, characteristic of positive feedback leading to physiological collapse rather
than homeostasis.
Q8: A patient has a pituitary tumor that causes constant, unregulated secretion of Thyroid
Stimulating Hormone (TSH). As a result, thyroid hormone levels are dangerously high, but the
.
Portage Learning (2026/2027)
Section 1: Principles of Homeostasis & Feedback Loops
Q1: Which of the following best defines the term "homeostasis"?
A. The inability of the body to maintain internal conditions when external conditions change
B. The maintenance of a relatively stable internal environment despite fluctuations in the
external environment
C. A state of unchanging physiological parameters that require no energy expenditure
D. The continuous directional change of internal conditions to match the external environment
Correct Answer: B
Rationale: Homeostasis is the active maintenance of stable internal conditions (like temperature
or pH) regardless of external changes; it is not passive, unchanging, or a matching process.
Q2: A marathon runner's body temperature increases to 39.2°C during a race but returns to 37°C
an hour after finishing. The fact that the body allowed the temperature to rise to 39.2°C without
immediate correction demonstrates which concept?
A. Set point failure
B. Positive feedback
C. Normal range variability
D. Effector fatigue
Correct Answer: C
Rationale: Homeostasis maintains parameters within a normal, safe range around a set point,
allowing temporary deviations like a mild fever or exercise-induced heat before initiating
corrective mechanisms.
.
,Q3: A patient eats a high-carbohydrate meal, causing blood glucose to rise. Pancreatic beta cells
detect this change and release insulin, which stimulates cells to take up glucose, lowering blood
glucose levels. In this scenario, what is the effector?
A. The elevated blood glucose
B. The pancreatic beta cells
C. The body cells that take up glucose
D. The blood vessels supplying the pancreas
Correct Answer: C
Rationale: The effector is the component that carries out the response to restore homeostasis;
here, it is the body cells taking up glucose, while the pancreatic beta cells act as the
sensor/control center.
Q4: What is the primary purpose of a negative feedback loop in human physiology?
A. To amplify a physiological response until an external intervention stops it
B. To continuously increase the production of a specific hormone
C. To reverse a deviation from a set point and restore equilibrium
D. To establish a new, higher baseline for a physiological parameter
Correct Answer: C
Rationale: Negative feedback loops are designed to detect deviations from a set point and
activate effectors to reverse the change, thereby maintaining equilibrium rather than amplifying
it.
Q5: A patient cuts their finger. Platelets adhere to the site and release chemicals that attract more
platelets, rapidly forming a plug. This is an example of:
A. Negative feedback because it stops bleeding
B. Positive feedback because it amplifies the initial platelet accumulation
C. Negative feedback because it prevents excessive blood loss
D. Positive feedback because it lowers blood pressure
Correct Answer: B
.
, Rationale: Blood clotting is a classic positive feedback loop where the initial event (platelet
adhesion) triggers the release of chemicals that enhance further platelet accumulation, amplifying
the response until the clot is formed.
Q6: During labor, the pressure of the baby's head on the cervix stimulates oxytocin release,
which causes stronger uterine contractions. This cycle continues until birth. Why is this
considered positive feedback rather than negative feedback?
A. Because the stimulus (cervical stretch) is amplified rather than reversed by the response
B. Because it involves the endocrine system instead of the nervous system
C. Because the outcome (birth) reverses the initial stimulus
D. Because oxytocin levels decrease immediately after the baby is born
Correct Answer: A
Rationale: Positive feedback amplifies the initial stimulus to drive a process to completion; the
contractions increase cervical stretch, which causes more contractions, rather than reversing the
stretch as negative feedback would.
Q7: A patient experiences a massive hemorrhage, causing blood pressure to drop so severely that
the heart cannot pump effectively, leading to further drops in blood pressure and cardiac output.
This deteriorating cycle is best described as:
A. Homeostatic compensation
B. A negative feedback loop restoring blood volume
C. A positive feedback loop creating a vicious cycle
D. An effector successfully opposing the stimulus
Correct Answer: C
Rationale: A vicious cycle occurs when a stimulus triggers a response that further exacerbates
the initial problem, characteristic of positive feedback leading to physiological collapse rather
than homeostasis.
Q8: A patient has a pituitary tumor that causes constant, unregulated secretion of Thyroid
Stimulating Hormone (TSH). As a result, thyroid hormone levels are dangerously high, but the
.
