BIOL180 Practice Exam 9 Animal
Physiology Questions And Correct
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1. Which statement best describes homeostasis in animals?
A. Maintenance of an unchanging internal environment regardless
of external conditions
B. Elimination of all variation in physiological processes
C. Maintenance of relatively stable internal conditions through
regulatory mechanisms
D. Adjustment of internal conditions only when environmental
conditions are extreme
Answer: C. Maintenance of relatively stable internal conditions
through regulatory mechanisms
Rationale: Homeostasis refers to the maintenance of relatively stable
internal conditions despite changes in the external environment. It
does not mean that physiological variables remain absolutely constant.
Instead, variables such as temperature, blood glucose, pH, and
osmolarity fluctuate within regulated ranges. Negative feedback is one
of the most important mechanisms animals use to maintain these
variables near appropriate set points.
2. Which component of a homeostatic control system detects a
change in a physiological variable?
A. Receptor or sensor
, B. Effector
C. Control center
D. Hormone
Answer: A. Receptor or sensor
Rationale: A receptor or sensor detects changes in a regulated
physiological variable and sends information to a control center. The
control center evaluates the information and determines an
appropriate response, while an effector carries out that response. For
example, thermoreceptors detect changes in body temperature,
allowing the nervous system to activate mechanisms that increase or
decrease heat loss.
3. Negative feedback is characterized by which response?
A. A response that always increases the original stimulus
B. A response that eliminates all physiological variation
C. A response that occurs only during disease
D. A response that counteracts the initial change
Answer: D. A response that counteracts the initial change
Rationale: Negative feedback opposes the direction of an initial
disturbance and thereby helps stabilize a physiological variable. For
example, when blood glucose rises after a meal, insulin promotes
glucose uptake and storage, causing blood glucose to decrease toward
its normal range. Negative feedback is therefore fundamental to
homeostasis in animals.
4. Which example represents positive feedback?
A. Regulation of body temperature
B. Uterine contractions during childbirth
C. Regulation of blood glucose
D. Regulation of blood calcium
,Answer: B. Uterine contractions during childbirth
Rationale: Positive feedback amplifies an initial stimulus rather than
opposing it. During childbirth, stretching of the cervix stimulates
oxytocin release, which increases uterine contractions. Stronger
contractions increase cervical stretching, producing additional
oxytocin release. This cycle continues until the baby is delivered,
terminating the stimulus and therefore ending the positive-feedback
loop.
5. What is the primary function of an animal nervous system?
A. Rapid communication and coordination of physiological
responses
B. Production of red blood cells
C. Long-term storage of metabolic waste
D. Digestion of macromolecules
Answer: A. Rapid communication and coordination of physiological
responses
Rationale: The nervous system provides rapid communication
throughout the body. Neurons transmit electrical signals, while
chemical neurotransmitters communicate between cells. This allows
animals to rapidly detect environmental changes and coordinate
movements, sensory responses, and internal physiological processes.
The endocrine system also coordinates body functions, but its effects
are generally slower and often longer lasting.
6. Which cell is the functional unit of the nervous system?
A. Erythrocyte
B. Osteocyte
C. Neuron
D. Adipocyte
, Answer: C. Neuron
Rationale: Neurons are specialized cells capable of receiving,
processing, and transmitting information. They commonly contain
dendrites that receive signals, a cell body that contains the nucleus,
and an axon that transmits electrical impulses toward other cells.
Supporting glial cells are also essential to nervous-system function,
but neurons are the principal signaling cells.
7. What is the resting membrane potential of a typical neuron
primarily produced by?
A. Equal concentrations of ions on both sides of the membrane
B. Ion concentration gradients and selective membrane
permeability
C. Continuous opening of all voltage-gated channels
D. Complete absence of potassium ions inside the neuron
Answer: B. Ion concentration gradients and selective membrane
permeability
Rationale: A neuron's resting membrane potential results from
unequal ion distributions across the plasma membrane and selective
permeability to those ions. Potassium contributes strongly because
resting membranes are relatively permeable to potassium. The sodium-
potassium pump maintains ion gradients by moving sodium outward
and potassium inward. Together, these mechanisms create a negative
electrical potential inside the resting neuron.
8. What event initiates an action potential when a neuron reaches
threshold?
A. Opening of voltage-gated sodium channels
B. Closing of all potassium channels
Physiology Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. Which statement best describes homeostasis in animals?
A. Maintenance of an unchanging internal environment regardless
of external conditions
B. Elimination of all variation in physiological processes
C. Maintenance of relatively stable internal conditions through
regulatory mechanisms
D. Adjustment of internal conditions only when environmental
conditions are extreme
Answer: C. Maintenance of relatively stable internal conditions
through regulatory mechanisms
Rationale: Homeostasis refers to the maintenance of relatively stable
internal conditions despite changes in the external environment. It
does not mean that physiological variables remain absolutely constant.
Instead, variables such as temperature, blood glucose, pH, and
osmolarity fluctuate within regulated ranges. Negative feedback is one
of the most important mechanisms animals use to maintain these
variables near appropriate set points.
2. Which component of a homeostatic control system detects a
change in a physiological variable?
A. Receptor or sensor
, B. Effector
C. Control center
D. Hormone
Answer: A. Receptor or sensor
Rationale: A receptor or sensor detects changes in a regulated
physiological variable and sends information to a control center. The
control center evaluates the information and determines an
appropriate response, while an effector carries out that response. For
example, thermoreceptors detect changes in body temperature,
allowing the nervous system to activate mechanisms that increase or
decrease heat loss.
3. Negative feedback is characterized by which response?
A. A response that always increases the original stimulus
B. A response that eliminates all physiological variation
C. A response that occurs only during disease
D. A response that counteracts the initial change
Answer: D. A response that counteracts the initial change
Rationale: Negative feedback opposes the direction of an initial
disturbance and thereby helps stabilize a physiological variable. For
example, when blood glucose rises after a meal, insulin promotes
glucose uptake and storage, causing blood glucose to decrease toward
its normal range. Negative feedback is therefore fundamental to
homeostasis in animals.
4. Which example represents positive feedback?
A. Regulation of body temperature
B. Uterine contractions during childbirth
C. Regulation of blood glucose
D. Regulation of blood calcium
,Answer: B. Uterine contractions during childbirth
Rationale: Positive feedback amplifies an initial stimulus rather than
opposing it. During childbirth, stretching of the cervix stimulates
oxytocin release, which increases uterine contractions. Stronger
contractions increase cervical stretching, producing additional
oxytocin release. This cycle continues until the baby is delivered,
terminating the stimulus and therefore ending the positive-feedback
loop.
5. What is the primary function of an animal nervous system?
A. Rapid communication and coordination of physiological
responses
B. Production of red blood cells
C. Long-term storage of metabolic waste
D. Digestion of macromolecules
Answer: A. Rapid communication and coordination of physiological
responses
Rationale: The nervous system provides rapid communication
throughout the body. Neurons transmit electrical signals, while
chemical neurotransmitters communicate between cells. This allows
animals to rapidly detect environmental changes and coordinate
movements, sensory responses, and internal physiological processes.
The endocrine system also coordinates body functions, but its effects
are generally slower and often longer lasting.
6. Which cell is the functional unit of the nervous system?
A. Erythrocyte
B. Osteocyte
C. Neuron
D. Adipocyte
, Answer: C. Neuron
Rationale: Neurons are specialized cells capable of receiving,
processing, and transmitting information. They commonly contain
dendrites that receive signals, a cell body that contains the nucleus,
and an axon that transmits electrical impulses toward other cells.
Supporting glial cells are also essential to nervous-system function,
but neurons are the principal signaling cells.
7. What is the resting membrane potential of a typical neuron
primarily produced by?
A. Equal concentrations of ions on both sides of the membrane
B. Ion concentration gradients and selective membrane
permeability
C. Continuous opening of all voltage-gated channels
D. Complete absence of potassium ions inside the neuron
Answer: B. Ion concentration gradients and selective membrane
permeability
Rationale: A neuron's resting membrane potential results from
unequal ion distributions across the plasma membrane and selective
permeability to those ions. Potassium contributes strongly because
resting membranes are relatively permeable to potassium. The sodium-
potassium pump maintains ion gradients by moving sodium outward
and potassium inward. Together, these mechanisms create a negative
electrical potential inside the resting neuron.
8. What event initiates an action potential when a neuron reaches
threshold?
A. Opening of voltage-gated sodium channels
B. Closing of all potassium channels
