Principles of Human Physiology 6th Edition
Stanfield Complete Test Bank: Chapters 1-
24 Verified Exam Questions & Rationales
Question 1
Which of the following best describes the concept of homeostasis?
A) The body's ability to completely prevent any internal changes from occurring.
B) The maintenance of a relatively constant internal environment despite external variations.
C) The continuous fluctuation of the internal environment to match the external climate.
D) The exclusive regulation of blood pressure by a single organ system.
VERIFIED ANSWER: B) The maintenance of a relatively constant internal environment
despite external variations.
, EXPLANATION: Homeostasis is not a static, unchanging state; rather, it represents a
dynamic equilibrium. The body uses regulatory mechanisms to maintain variables (such as
temperature, pH, and ion concentrations) within a narrow, predictable range necessary for
cellular survival, even when the external surroundings change dramatically.
Question 2
In a negative feedback loop, what is the primary role of the sensor (receptor)?
A) To change the internal conditions back to the set point.
B) To process information and make a decision on the response.
C) To detect deviations from the set point and send signals to the integrating center.
D) To execute the final biological action that opposes the initial stimulus.
VERIFIED ANSWER: C) To detect deviations from the set point and send signals to the
integrating center.
EXPLANATION: The sensor's exact job is to monitor a specific physiological variable.
When that variable drifts from its baseline set point, the sensor detects the shift and
transmits an afferent signal to the integrating (or control) center, which then determines
the appropriate corrective response.
Question 3
Which of the following scenarios is an example of a positive feedback mechanism?
A) The release of insulin following an increase in blood glucose levels.
B) The shivering response triggered by a drop in core body temperature.
C) The secretion of oxytocin during childbirth to increase uterine contractions.
D) The reduction of heart rate when arterial blood pressure rises too high.
VERIFIED ANSWER: C) The secretion of oxytocin during childbirth to increase uterine
contractions.
EXPLANATION: Unlike negative feedback, which reverses a trend, positive feedback
amplifies a stimulus, moving the system further away from its initial state to complete a
specific process. During labor, uterine contractions trigger oxytocin release, which causes
stronger contractions, culminating in childbirth.
Chapter 2: Cell Structure and Function
, Question 4
Which organelle is primarily responsible for the synthesis of lipids and the detoxification of
drugs within human cells?
A) Rough endoplasmic reticulum
B) Smooth endoplasmic reticulum
C) Golgi apparatus
D) Lysosome
VERIFIED ANSWER: B) Smooth endoplasmic reticulum
EXPLANATION: The smooth endoplasmic reticulum (SER) lacks ribosomes and
specializes in lipid synthesis, steroid hormone production, and the detoxification of
metabolic byproducts or foreign toxins. The rough endoplasmic reticulum (RER), by
contrast, is covered in ribosomes and specializes in protein synthesis.
Question 5
What is the structural function of the cholesterol molecules embedded within the plasma
membrane?
A) To serve as primary channels for the active transport of sodium ions.
B) To stabilize membrane fluidity across varying physiological temperatures.
C) To act as cell surface receptors for hydrophilic peptide hormones.
D) To catalyze the breakdown of metabolic wastes outside the cell.
VERIFIED ANSWER: B) To stabilize membrane fluidity across varying physiological
temperatures.
EXPLANATION: Cholesterol acts as a fluidity buffer within the lipid bilayer. At high
temperatures, it restrains phospholipid movement to prevent the membrane from becoming
too fluid; at low temperatures, it prevents the phospholipids from packing tightly together
and crystallizing, thereby maintaining optimal membrane flexibility.
Question 6
Which cytoskeletal filament forms the mitotic spindle during cell division and acts as a
trackway for intracellular transport via motor proteins?
A) Microfilaments (actin)
B) Intermediate filaments (keratin)
C) Microtubules
D) Peroxisomes
, VERIFIED ANSWER: C) Microtubules
EXPLANATION: Microtubules are large, hollow tubes made of tubulin subunits. They
are essential for maintaining cell shape, forming the mitotic spindle that segregates
chromosomes during mitosis, and serving as structural tracks for kinesin and dynein motor
proteins to move organelles.
Chapter 3: Cell Metabolism
Question 7
During glycolysis, what is the net yield of ATP and NADH produced from a single molecule
of glucose?
A) 4 ATP, 4 NADH
B) 2 ATP, 2 NADH
C) 32 ATP, 10 NADH
D) 2 ATP, 0 NADH
VERIFIED ANSWER: B) 2 ATP, 2 NADH
EXPLANATION: Glycolysis breaks down one 6-carbon glucose molecule into two 3-
carbon pyruvate molecules. While the process generates 4 total ATP molecules during its
energy-payoff phase, it consumes 2 ATP during the investment phase, resulting in a net
gain of 2 ATP and 2 reduction equivalents of NADH.
Question 8
What is the direct role of oxygen (\(O_{2}\)) in cellular respiration?
A) To act as the final electron acceptor at the end of the electron transport chain.
B) To bind with carbon to produce carbon dioxide during the Krebs cycle.
C) To directly phosphorylate ADP into ATP inside the mitochondrial matrix.
D) To break down pyruvate into acetyl-CoA in the cytoplasm.
VERIFIED ANSWER: A) To act as the final electron acceptor at the end of the electron
transport chain.
EXPLANATION: Oxygen is required at the very end of the oxidative phosphorylation
pathway. It accepts spent, low-energy electrons from complex IV and binds with hydrogen
Stanfield Complete Test Bank: Chapters 1-
24 Verified Exam Questions & Rationales
Question 1
Which of the following best describes the concept of homeostasis?
A) The body's ability to completely prevent any internal changes from occurring.
B) The maintenance of a relatively constant internal environment despite external variations.
C) The continuous fluctuation of the internal environment to match the external climate.
D) The exclusive regulation of blood pressure by a single organ system.
VERIFIED ANSWER: B) The maintenance of a relatively constant internal environment
despite external variations.
, EXPLANATION: Homeostasis is not a static, unchanging state; rather, it represents a
dynamic equilibrium. The body uses regulatory mechanisms to maintain variables (such as
temperature, pH, and ion concentrations) within a narrow, predictable range necessary for
cellular survival, even when the external surroundings change dramatically.
Question 2
In a negative feedback loop, what is the primary role of the sensor (receptor)?
A) To change the internal conditions back to the set point.
B) To process information and make a decision on the response.
C) To detect deviations from the set point and send signals to the integrating center.
D) To execute the final biological action that opposes the initial stimulus.
VERIFIED ANSWER: C) To detect deviations from the set point and send signals to the
integrating center.
EXPLANATION: The sensor's exact job is to monitor a specific physiological variable.
When that variable drifts from its baseline set point, the sensor detects the shift and
transmits an afferent signal to the integrating (or control) center, which then determines
the appropriate corrective response.
Question 3
Which of the following scenarios is an example of a positive feedback mechanism?
A) The release of insulin following an increase in blood glucose levels.
B) The shivering response triggered by a drop in core body temperature.
C) The secretion of oxytocin during childbirth to increase uterine contractions.
D) The reduction of heart rate when arterial blood pressure rises too high.
VERIFIED ANSWER: C) The secretion of oxytocin during childbirth to increase uterine
contractions.
EXPLANATION: Unlike negative feedback, which reverses a trend, positive feedback
amplifies a stimulus, moving the system further away from its initial state to complete a
specific process. During labor, uterine contractions trigger oxytocin release, which causes
stronger contractions, culminating in childbirth.
Chapter 2: Cell Structure and Function
, Question 4
Which organelle is primarily responsible for the synthesis of lipids and the detoxification of
drugs within human cells?
A) Rough endoplasmic reticulum
B) Smooth endoplasmic reticulum
C) Golgi apparatus
D) Lysosome
VERIFIED ANSWER: B) Smooth endoplasmic reticulum
EXPLANATION: The smooth endoplasmic reticulum (SER) lacks ribosomes and
specializes in lipid synthesis, steroid hormone production, and the detoxification of
metabolic byproducts or foreign toxins. The rough endoplasmic reticulum (RER), by
contrast, is covered in ribosomes and specializes in protein synthesis.
Question 5
What is the structural function of the cholesterol molecules embedded within the plasma
membrane?
A) To serve as primary channels for the active transport of sodium ions.
B) To stabilize membrane fluidity across varying physiological temperatures.
C) To act as cell surface receptors for hydrophilic peptide hormones.
D) To catalyze the breakdown of metabolic wastes outside the cell.
VERIFIED ANSWER: B) To stabilize membrane fluidity across varying physiological
temperatures.
EXPLANATION: Cholesterol acts as a fluidity buffer within the lipid bilayer. At high
temperatures, it restrains phospholipid movement to prevent the membrane from becoming
too fluid; at low temperatures, it prevents the phospholipids from packing tightly together
and crystallizing, thereby maintaining optimal membrane flexibility.
Question 6
Which cytoskeletal filament forms the mitotic spindle during cell division and acts as a
trackway for intracellular transport via motor proteins?
A) Microfilaments (actin)
B) Intermediate filaments (keratin)
C) Microtubules
D) Peroxisomes
, VERIFIED ANSWER: C) Microtubules
EXPLANATION: Microtubules are large, hollow tubes made of tubulin subunits. They
are essential for maintaining cell shape, forming the mitotic spindle that segregates
chromosomes during mitosis, and serving as structural tracks for kinesin and dynein motor
proteins to move organelles.
Chapter 3: Cell Metabolism
Question 7
During glycolysis, what is the net yield of ATP and NADH produced from a single molecule
of glucose?
A) 4 ATP, 4 NADH
B) 2 ATP, 2 NADH
C) 32 ATP, 10 NADH
D) 2 ATP, 0 NADH
VERIFIED ANSWER: B) 2 ATP, 2 NADH
EXPLANATION: Glycolysis breaks down one 6-carbon glucose molecule into two 3-
carbon pyruvate molecules. While the process generates 4 total ATP molecules during its
energy-payoff phase, it consumes 2 ATP during the investment phase, resulting in a net
gain of 2 ATP and 2 reduction equivalents of NADH.
Question 8
What is the direct role of oxygen (\(O_{2}\)) in cellular respiration?
A) To act as the final electron acceptor at the end of the electron transport chain.
B) To bind with carbon to produce carbon dioxide during the Krebs cycle.
C) To directly phosphorylate ADP into ATP inside the mitochondrial matrix.
D) To break down pyruvate into acetyl-CoA in the cytoplasm.
VERIFIED ANSWER: A) To act as the final electron acceptor at the end of the electron
transport chain.
EXPLANATION: Oxygen is required at the very end of the oxidative phosphorylation
pathway. It accepts spent, low-energy electrons from complex IV and binds with hydrogen
