OpenStax Psychology Chapter 3 Test
Bank: Biopsychology Questions & Answers
(Verified Exam Prep)
Question 1
Which of the following fields of study focuses specifically on how the underlying genetic
blueprint interacts with environmental factors to express traits without altering the actual
DNA sequence?
,A) Behavioral genetics
B) Evolutionary psychology
C) Epigenetics
D) Sociobiology
ANSWER: C) Epigenetics
EXPLANATION: Epigenetics investigates how environmental factors (such as stress, diet,
and toxins) can change gene expression by turning genes on or off, all without changing
the underlying DNA sequence. Behavioral genetics studies the overall balance of nature
and nurture, while evolutionary psychology looks at universal adaptations over millennia.
Question 2
An individual's complete genetic makeup is referred to as their ________, whereas their
physical, observable characteristics resulting from the interaction of those genes and the
environment is known as their ________.
A) phenotype; genotype
B) allele; chromosome
C) genotype; phenotype
D) chromosome; allele
ANSWER: C) genotype; phenotype
EXPLANATION: The genotype is the exact genetic code or blueprint inherited from the
parents. The phenotype is the physical, behavioral, and biochemical expression of that
genotype as it interacts with environmental conditions over time.
Question 3
Most human traits and psychological disorders, such as schizophrenia or depression, are not
controlled by a single gene pair. Instead, they are influenced by the combined action of
multiple genes, a phenomenon known as:
A) Homozygous expression
B) Polygenic inheritance
C) Heterozygous dominance
D) Mutation sequencing
,ANSWER: B) Polygenic inheritance
EXPLANATION: Polygenic inheritance occurs when a single trait or disorder is regulated
by the interaction of more than one gene. Psychological characteristics and complex
behavioral conditions are almost exclusively polygenic.
Question 4
Which component of the neuron acts as the primary receiver of incoming chemical signals or
neurotransmitters sent from neighboring cells?
A) Axon
B) Dendrite
C) Myelin sheath
D) Terminal button
ANSWER: B) Dendrite
EXPLANATION: Dendrites are branching extensions that project from the cell body
(soma). They serve as input sites where signals are received from other neurons. Axons
carry signals away from the cell body, and terminal buttons release neurotransmitters.
Question 5
What is the function of the myelin sheath that covers the axon of many central and peripheral
nervous system neurons?
A) It synthesizes chemical neurotransmitters for rapid synaptic release.
B) It acts as an electrical insulator to speed up the transmission of the action potential.
C) It serves as a structural barrier that blocks all sodium and potassium ions from entering.
D) It reabsorbs excess dopamine and serotonin from the synaptic cleft.
ANSWER: B) It acts as an electrical insulator to speed up the transmission of the action
potential.
EXPLANATION: The myelin sheath is a fatty layer formed by glial cells that insulates the
axon. This insulation allows the action potential to skip rapidly from one node of Ranvier
to the next via saltatory conduction, greatly increasing transmission speed.
Question 6
When a neuron is at its resting potential, the charge across its membrane is roughly -70
millivolts. Which of the following describes the ion distribution maintaining this state?
, A) High concentration of sodium (Na+) inside the cell, high concentration of potassium (K+)
outside.
B) Equal concentrations of sodium (Na+) and potassium (K+) on both sides of the membrane.
C) High concentration of potassium (K+) inside the cell, high concentration of sodium (Na+)
outside.
D) High concentration of negatively charged proteins floating in the extracellular fluid.
ANSWER: C) High concentration of potassium (K+) inside the cell, high concentration of
sodium (Na+) outside.
EXPLANATION: At resting potential, the intracellular fluid is more negative than the
extracellular fluid (-70 mV). Potassium (K+) is more heavily concentrated inside the
neuron, while sodium (Na+) remains highly concentrated in the fluid outside the cell. This
balance is maintained by the sodium-potassium pump.
Question 7
The "all-or-none" principle of neural firing dictates that which of the following statements is
true?
A) A stronger incoming stimulus causes the action potential to travel significantly faster
down the axon.
B) A neuron will fire an action potential of the exact same size and intensity every time its
threshold of excitation is crossed.
C) If a stimulus is incredibly intense, the neuron will release larger, more powerful action
potentials.
D) The neuron must fire all its stored neurotransmitters simultaneously, or it will not fire at
all.
ANSWER: B) A neuron will fire an action potential of the exact same size and intensity
every time its threshold of excitation is crossed.
EXPLANATION: The all-or-none characteristic means that an action potential is binary:
it either triggers fully at a consistent amplitude and speed once the threshold (-55 mV) is
passed, or it does not fire at all. Stimulus intensity is encoded by the frequency of firing,
not the size or speed of individual action potentials.
Question 8
Bank: Biopsychology Questions & Answers
(Verified Exam Prep)
Question 1
Which of the following fields of study focuses specifically on how the underlying genetic
blueprint interacts with environmental factors to express traits without altering the actual
DNA sequence?
,A) Behavioral genetics
B) Evolutionary psychology
C) Epigenetics
D) Sociobiology
ANSWER: C) Epigenetics
EXPLANATION: Epigenetics investigates how environmental factors (such as stress, diet,
and toxins) can change gene expression by turning genes on or off, all without changing
the underlying DNA sequence. Behavioral genetics studies the overall balance of nature
and nurture, while evolutionary psychology looks at universal adaptations over millennia.
Question 2
An individual's complete genetic makeup is referred to as their ________, whereas their
physical, observable characteristics resulting from the interaction of those genes and the
environment is known as their ________.
A) phenotype; genotype
B) allele; chromosome
C) genotype; phenotype
D) chromosome; allele
ANSWER: C) genotype; phenotype
EXPLANATION: The genotype is the exact genetic code or blueprint inherited from the
parents. The phenotype is the physical, behavioral, and biochemical expression of that
genotype as it interacts with environmental conditions over time.
Question 3
Most human traits and psychological disorders, such as schizophrenia or depression, are not
controlled by a single gene pair. Instead, they are influenced by the combined action of
multiple genes, a phenomenon known as:
A) Homozygous expression
B) Polygenic inheritance
C) Heterozygous dominance
D) Mutation sequencing
,ANSWER: B) Polygenic inheritance
EXPLANATION: Polygenic inheritance occurs when a single trait or disorder is regulated
by the interaction of more than one gene. Psychological characteristics and complex
behavioral conditions are almost exclusively polygenic.
Question 4
Which component of the neuron acts as the primary receiver of incoming chemical signals or
neurotransmitters sent from neighboring cells?
A) Axon
B) Dendrite
C) Myelin sheath
D) Terminal button
ANSWER: B) Dendrite
EXPLANATION: Dendrites are branching extensions that project from the cell body
(soma). They serve as input sites where signals are received from other neurons. Axons
carry signals away from the cell body, and terminal buttons release neurotransmitters.
Question 5
What is the function of the myelin sheath that covers the axon of many central and peripheral
nervous system neurons?
A) It synthesizes chemical neurotransmitters for rapid synaptic release.
B) It acts as an electrical insulator to speed up the transmission of the action potential.
C) It serves as a structural barrier that blocks all sodium and potassium ions from entering.
D) It reabsorbs excess dopamine and serotonin from the synaptic cleft.
ANSWER: B) It acts as an electrical insulator to speed up the transmission of the action
potential.
EXPLANATION: The myelin sheath is a fatty layer formed by glial cells that insulates the
axon. This insulation allows the action potential to skip rapidly from one node of Ranvier
to the next via saltatory conduction, greatly increasing transmission speed.
Question 6
When a neuron is at its resting potential, the charge across its membrane is roughly -70
millivolts. Which of the following describes the ion distribution maintaining this state?
, A) High concentration of sodium (Na+) inside the cell, high concentration of potassium (K+)
outside.
B) Equal concentrations of sodium (Na+) and potassium (K+) on both sides of the membrane.
C) High concentration of potassium (K+) inside the cell, high concentration of sodium (Na+)
outside.
D) High concentration of negatively charged proteins floating in the extracellular fluid.
ANSWER: C) High concentration of potassium (K+) inside the cell, high concentration of
sodium (Na+) outside.
EXPLANATION: At resting potential, the intracellular fluid is more negative than the
extracellular fluid (-70 mV). Potassium (K+) is more heavily concentrated inside the
neuron, while sodium (Na+) remains highly concentrated in the fluid outside the cell. This
balance is maintained by the sodium-potassium pump.
Question 7
The "all-or-none" principle of neural firing dictates that which of the following statements is
true?
A) A stronger incoming stimulus causes the action potential to travel significantly faster
down the axon.
B) A neuron will fire an action potential of the exact same size and intensity every time its
threshold of excitation is crossed.
C) If a stimulus is incredibly intense, the neuron will release larger, more powerful action
potentials.
D) The neuron must fire all its stored neurotransmitters simultaneously, or it will not fire at
all.
ANSWER: B) A neuron will fire an action potential of the exact same size and intensity
every time its threshold of excitation is crossed.
EXPLANATION: The all-or-none characteristic means that an action potential is binary:
it either triggers fully at a consistent amplitude and speed once the threshold (-55 mV) is
passed, or it does not fire at all. Stimulus intensity is encoded by the frequency of firing,
not the size or speed of individual action potentials.
Question 8
