2026 BIOD 102 Module 3 Exam Portage Learning Questions
and Answers 2026
Section 1: Neurons & Action Potentials (1-15)
1. What is the standard resting membrane potential of a neuron?
• A) +30 mV
• B) -55 mV
• C) -70 mV
• D) 0 mV
• Correct: C. Rationale: The sodium-potassium pump and leak channels maintain
a polarized state where the inside is more negative than the outside at -70 mV.
2. Which ion is primarily responsible for the depolarization phase of an action
potential?
• A) K+ (Potassium)
• B) Cl- (Chloride)
• C) Na+ (Sodium)
• D) Mg2+ (Magnesium)
• Correct: C. Rationale: When the threshold is reached, voltage-gated sodium
channels open, allowing Na+ to rush into the cell, making the interior positive.
3. The "All-or-None" law states that:
• A) All neurons fire at the same time.
• B) A neuron fires completely or not at all once threshold is reached.
• C) Larger stimuli create larger action potentials.
• D) Only motor neurons use action potentials.
• Correct: B. Rationale: Action potentials do not vary in intensity; if the stimulus hits
-55 mV, the spike is always the same magnitude.
,4. What insulating layer increases the speed of impulse conduction?
• A) Synapse
• B) Dendrite
• C) Myelin Sheath
• D) Node of Ranvier
• Correct: C. Rationale: The myelin sheath acts as electrical insulation, allowing
the signal to "jump" between nodes via saltatory conduction.
5. Which gaps in the myelin sheath allow for saltatory conduction?
• A) Synaptic clefts
• B) Nodes of Ranvier
• C) Ganglia
• D) Axon hillocks
• Correct: B. Rationale: These gaps contain a high density of voltage-gated
channels where the action potential is regenerated.
6. What happens during repolarization?
• A) Na+ enters the cell
• B) K+ exits the cell
• C) Ca2+ enters the cell
• D) Cl- exits the cell
• Correct: B. Rationale: Sodium channels close and potassium channels open,
allowing K+ to leave the cell and restore the negative internal charge.
7. Hyperpolarization (the "undershoot") is caused by:
• A) Rapid influx of Na+
• B) Slow closing of K+ channels
• C) Failure of the Na/K pump
• D) Excessive Cl- leakage
, • Correct: B. Rationale: K+ channels stay open slightly too long, causing the
membrane potential to become more negative than the resting -70 mV.
8. Which structure releases neurotransmitters into the synapse?
• A) Dendrite
• B) Cell body (Soma)
• C) Axon terminal
• D) Nucleus
• Correct: C. Rationale: The axon terminal contains vesicles that release chemical
signals when triggered by an action potential.
9. What is the gap between two communicating neurons called?
• A) Bridge
• B) Synaptic cleft
• C) Junctional fold
• D) Interneuron
• Correct: B. Rationale: The cleft is the physical space where neurotransmitters
diffuse from the presynaptic to the postsynaptic neuron.
10. Which ion triggers the release of neurotransmitter vesicles?
• A) Na+
• B) K+
• C) Ca2+
• D) Fe2+
• Correct: C. Rationale: When the action potential reaches the terminal, voltage-
gated Calcium channels open; the influx of Ca2+ causes exocytosis of vesicles.
11. What is an IPSP (Inhibitory Postsynaptic Potential)?
• A) A small depolarization
• B) A small hyperpolarization
• C) A full action potential
and Answers 2026
Section 1: Neurons & Action Potentials (1-15)
1. What is the standard resting membrane potential of a neuron?
• A) +30 mV
• B) -55 mV
• C) -70 mV
• D) 0 mV
• Correct: C. Rationale: The sodium-potassium pump and leak channels maintain
a polarized state where the inside is more negative than the outside at -70 mV.
2. Which ion is primarily responsible for the depolarization phase of an action
potential?
• A) K+ (Potassium)
• B) Cl- (Chloride)
• C) Na+ (Sodium)
• D) Mg2+ (Magnesium)
• Correct: C. Rationale: When the threshold is reached, voltage-gated sodium
channels open, allowing Na+ to rush into the cell, making the interior positive.
3. The "All-or-None" law states that:
• A) All neurons fire at the same time.
• B) A neuron fires completely or not at all once threshold is reached.
• C) Larger stimuli create larger action potentials.
• D) Only motor neurons use action potentials.
• Correct: B. Rationale: Action potentials do not vary in intensity; if the stimulus hits
-55 mV, the spike is always the same magnitude.
,4. What insulating layer increases the speed of impulse conduction?
• A) Synapse
• B) Dendrite
• C) Myelin Sheath
• D) Node of Ranvier
• Correct: C. Rationale: The myelin sheath acts as electrical insulation, allowing
the signal to "jump" between nodes via saltatory conduction.
5. Which gaps in the myelin sheath allow for saltatory conduction?
• A) Synaptic clefts
• B) Nodes of Ranvier
• C) Ganglia
• D) Axon hillocks
• Correct: B. Rationale: These gaps contain a high density of voltage-gated
channels where the action potential is regenerated.
6. What happens during repolarization?
• A) Na+ enters the cell
• B) K+ exits the cell
• C) Ca2+ enters the cell
• D) Cl- exits the cell
• Correct: B. Rationale: Sodium channels close and potassium channels open,
allowing K+ to leave the cell and restore the negative internal charge.
7. Hyperpolarization (the "undershoot") is caused by:
• A) Rapid influx of Na+
• B) Slow closing of K+ channels
• C) Failure of the Na/K pump
• D) Excessive Cl- leakage
, • Correct: B. Rationale: K+ channels stay open slightly too long, causing the
membrane potential to become more negative than the resting -70 mV.
8. Which structure releases neurotransmitters into the synapse?
• A) Dendrite
• B) Cell body (Soma)
• C) Axon terminal
• D) Nucleus
• Correct: C. Rationale: The axon terminal contains vesicles that release chemical
signals when triggered by an action potential.
9. What is the gap between two communicating neurons called?
• A) Bridge
• B) Synaptic cleft
• C) Junctional fold
• D) Interneuron
• Correct: B. Rationale: The cleft is the physical space where neurotransmitters
diffuse from the presynaptic to the postsynaptic neuron.
10. Which ion triggers the release of neurotransmitter vesicles?
• A) Na+
• B) K+
• C) Ca2+
• D) Fe2+
• Correct: C. Rationale: When the action potential reaches the terminal, voltage-
gated Calcium channels open; the influx of Ca2+ causes exocytosis of vesicles.
11. What is an IPSP (Inhibitory Postsynaptic Potential)?
• A) A small depolarization
• B) A small hyperpolarization
• C) A full action potential
