BIOD 102 MODULE 4 EXAM 2026/2027 | Essential Biology II
with Lab | Verified Q&A | Grade A | Portage Learning | Pass
Guaranteed - A+ Graded
SECTION 1: HOMEOSTASIS & THERMOREGULATION (12 Questions)
Q1: Homeostasis is best defined as:
A. The active movement of molecules across a membrane against their concentration
gradient
B. The maintenance of relatively stable internal conditions despite changes in the
external environment [CORRECT]
C. The process of breaking down glucose to produce ATP
D. The transmission of electrical signals between neurons
Correct Answer: B
Rationale: Homeostasis refers to the physiological process by which organisms
maintain stable internal conditions (such as temperature, pH, and glucose levels)
despite external environmental fluctuations. Option A describes active transport, C
describes cellular respiration, and D describes neural signaling.
Q2: Which of the following represents a negative feedback mechanism?
A. Uterine contractions during labor, which intensify as oxytocin levels rise
B. Blood glucose regulation, where insulin release lowers blood glucose and
subsequently reduces further insulin secretion [CORRECT]
C. Platelet aggregation at a wound site, which recruits more platelets
D. Action potential generation in neurons, where depolarization triggers further
depolarization
Correct Answer: B
Rationale: Negative feedback counteracts a change to restore homeostasis; insulin
secretion decreases as blood glucose normalizes. Options A, C, and D describe positive
feedback loops where the response amplifies the initial stimulus.
Q3: A positive feedback mechanism is characterized by:
,A. A response that opposes the initial stimulus to maintain stability
B. A response that amplifies the initial stimulus, moving the system away from its
starting point [CORRECT]
C. The absence of any control center or effector involvement
D. Maintenance of a constant set point through receptor inhibition
Correct Answer: B
Rationale: Positive feedback amplifies the original stimulus, such as during blood
clotting or childbirth. Option A describes negative feedback, while C and D misrepresent
fundamental control system components.
Q4: In a homeostatic control system, the component that receives information about a
stimulus and initiates a response is the:
A. Receptor
B. Control center
C. Effector [CORRECT]
D. Afferent pathway
Correct Answer: C
Rationale: The effector is the muscle or gland that carries out the response directed by
the control center. The receptor detects the stimulus (A), the control center processes
the information (B), and the afferent pathway carries signals toward the CNS (D).
Q5: The "set point" in a homeostatic control system refers to:
A. The maximum temperature an organism can survive
B. The optimal value around which a physiological variable is regulated [CORRECT]
C. The threshold voltage required to trigger an action potential
D. The concentration of hormones in the bloodstream during stress
Correct Answer: B
Rationale: The set point is the target value (e.g., 37°C body temperature) that the control
system attempts to maintain. Options A, C, and D describe unrelated physiological
thresholds.
Q6: An ectothermic animal relies primarily on:
A. Metabolic heat production to maintain body temperature
B. Behavioral adaptations and external heat sources to regulate body temperature
[CORRECT]
C. Shivering thermogenesis to generate heat in cold environments
, D. Brown adipose tissue for non-shivering thermogenesis
Correct Answer: B
Rationale: Ectotherms (such as reptiles and amphibians) depend on environmental heat
sources and behaviors (basking, seeking shade) to regulate body temperature. Options
A, C, and D describe endothermic adaptations.
Q7: A lizard lying on a warm rock to raise its body temperature is an example of heat
exchange by:
A. Convection
B. Conduction [CORRECT]
C. Radiation
D. Evaporation
Correct Answer: B
Rationale: Conduction is heat transfer through direct contact between two surfaces.
Convection involves fluid movement (A), radiation involves electromagnetic waves (C),
and evaporation involves heat loss through liquid-to-gas phase change (D).
Q8: A dog panting on a hot day primarily uses which heat exchange mechanism?
A. Conduction
B. Convection
C. Radiation
D. Evaporation [CORRECT]
Correct Answer: D
Rationale: Panting increases evaporative heat loss from moist respiratory surfaces.
Conduction requires direct contact (A), convection requires air/fluid movement (B), and
radiation involves infrared heat emission (C).
Q9: Countercurrent heat exchange in the legs of arctic mammals functions to:
A. Increase heat loss from the body core to the extremities
B. Minimize heat loss by transferring heat from outgoing arterial blood to incoming
venous blood [CORRECT]
C. Facilitate evaporative cooling in the distal limbs
D. Increase blood flow to the skin surface for radiation
Correct Answer: B
with Lab | Verified Q&A | Grade A | Portage Learning | Pass
Guaranteed - A+ Graded
SECTION 1: HOMEOSTASIS & THERMOREGULATION (12 Questions)
Q1: Homeostasis is best defined as:
A. The active movement of molecules across a membrane against their concentration
gradient
B. The maintenance of relatively stable internal conditions despite changes in the
external environment [CORRECT]
C. The process of breaking down glucose to produce ATP
D. The transmission of electrical signals between neurons
Correct Answer: B
Rationale: Homeostasis refers to the physiological process by which organisms
maintain stable internal conditions (such as temperature, pH, and glucose levels)
despite external environmental fluctuations. Option A describes active transport, C
describes cellular respiration, and D describes neural signaling.
Q2: Which of the following represents a negative feedback mechanism?
A. Uterine contractions during labor, which intensify as oxytocin levels rise
B. Blood glucose regulation, where insulin release lowers blood glucose and
subsequently reduces further insulin secretion [CORRECT]
C. Platelet aggregation at a wound site, which recruits more platelets
D. Action potential generation in neurons, where depolarization triggers further
depolarization
Correct Answer: B
Rationale: Negative feedback counteracts a change to restore homeostasis; insulin
secretion decreases as blood glucose normalizes. Options A, C, and D describe positive
feedback loops where the response amplifies the initial stimulus.
Q3: A positive feedback mechanism is characterized by:
,A. A response that opposes the initial stimulus to maintain stability
B. A response that amplifies the initial stimulus, moving the system away from its
starting point [CORRECT]
C. The absence of any control center or effector involvement
D. Maintenance of a constant set point through receptor inhibition
Correct Answer: B
Rationale: Positive feedback amplifies the original stimulus, such as during blood
clotting or childbirth. Option A describes negative feedback, while C and D misrepresent
fundamental control system components.
Q4: In a homeostatic control system, the component that receives information about a
stimulus and initiates a response is the:
A. Receptor
B. Control center
C. Effector [CORRECT]
D. Afferent pathway
Correct Answer: C
Rationale: The effector is the muscle or gland that carries out the response directed by
the control center. The receptor detects the stimulus (A), the control center processes
the information (B), and the afferent pathway carries signals toward the CNS (D).
Q5: The "set point" in a homeostatic control system refers to:
A. The maximum temperature an organism can survive
B. The optimal value around which a physiological variable is regulated [CORRECT]
C. The threshold voltage required to trigger an action potential
D. The concentration of hormones in the bloodstream during stress
Correct Answer: B
Rationale: The set point is the target value (e.g., 37°C body temperature) that the control
system attempts to maintain. Options A, C, and D describe unrelated physiological
thresholds.
Q6: An ectothermic animal relies primarily on:
A. Metabolic heat production to maintain body temperature
B. Behavioral adaptations and external heat sources to regulate body temperature
[CORRECT]
C. Shivering thermogenesis to generate heat in cold environments
, D. Brown adipose tissue for non-shivering thermogenesis
Correct Answer: B
Rationale: Ectotherms (such as reptiles and amphibians) depend on environmental heat
sources and behaviors (basking, seeking shade) to regulate body temperature. Options
A, C, and D describe endothermic adaptations.
Q7: A lizard lying on a warm rock to raise its body temperature is an example of heat
exchange by:
A. Convection
B. Conduction [CORRECT]
C. Radiation
D. Evaporation
Correct Answer: B
Rationale: Conduction is heat transfer through direct contact between two surfaces.
Convection involves fluid movement (A), radiation involves electromagnetic waves (C),
and evaporation involves heat loss through liquid-to-gas phase change (D).
Q8: A dog panting on a hot day primarily uses which heat exchange mechanism?
A. Conduction
B. Convection
C. Radiation
D. Evaporation [CORRECT]
Correct Answer: D
Rationale: Panting increases evaporative heat loss from moist respiratory surfaces.
Conduction requires direct contact (A), convection requires air/fluid movement (B), and
radiation involves infrared heat emission (C).
Q9: Countercurrent heat exchange in the legs of arctic mammals functions to:
A. Increase heat loss from the body core to the extremities
B. Minimize heat loss by transferring heat from outgoing arterial blood to incoming
venous blood [CORRECT]
C. Facilitate evaporative cooling in the distal limbs
D. Increase blood flow to the skin surface for radiation
Correct Answer: B
