BIOD 152 Final:BIOD 152 Final Exam: 50 Questions & Answers: Latest Updated A+ Score Solution Guide

BIOD 152 Final Exam: Questions & Answers: Latest Updated
Module 1: Nervous System & Synaptic Physiology
1. For a neuron with an initial membrane potential of -70 mV, an increase in the
movement of potassium ions out of that neuron's cytoplasm would result in
which of the following?
• A) Depolarization of the neuron
• B) Hyperpolarization of the neuron
• C) Repolarization of the neuron
• D) No change in membrane potential
• Correct Answer: B
• Explanation: Increased efflux of potassium ions (positive charges leaving
the cell) makes the interior of the cell more negative, resulting in
hyperpolarization.
2. The operation of the sodium-potassium "pump" moves:
• A) Sodium ions into the cell and potassium ions out of the cell
• B) Sodium ions out of the cell and potassium ions into the cell
• C) Both sodium and potassium ions out of the cell
• D) Both sodium and potassium ions into the cell
• Correct Answer: B
• Explanation: The active transport of the sodium-potassium pump moves
sodium ions out of the cytoplasm and brings potassium ions into the cell to
maintain resting concentrations.
3. What directly powers the movement of Na+ out of cells via the sodium-
potassium pump?
• A) Simple diffusion

, • B) ATP hydrolysis
• C) Facilitated diffusion
• D) Passive leak channels
• Correct Answer: B
• Explanation: The active transport of sodium out of cells is directly powered
by ATP hydrolysis.
4. The "threshold" potential of a neuron's membrane is defined as the:
• A) Maximum depolarization of an action potential
• B) Minimum depolarization needed to operate the voltage-gated sodium
and voltage-gated potassium channels
• C) Point at which the cell hyperpolarizes below -70 mV
• D) Membrane potential when the cell is at rest
• Correct Answer: B
• Explanation: The threshold potential is the minimum level of depolarization
required to open the voltage-gated sodium and potassium channels to
generate an action potential.
5. A neuron membrane's permeability to sodium ions is at its maximum at:
• A) -70 mV
• B) -50 mV
• C) +40 mV
• D) -90 mV
• Correct Answer: B
• Explanation: Permeability to sodium reaches its peak during the rising
phase of depolarization at -50 mV.

, 6. If the activity of the sodium-potassium pump is completely stopped, what
would happen to the neuron's membrane potential?
• A) Immediate loss of action potential
• B) Slow decrease of resting potential
• C) Immediate hyperpolarization of the cell
• D) Sudden increase in action potential height
• Correct Answer: B
• Explanation: Stopping the pump halts the active maintenance of ion
gradients, leading to a slow, gradual decrease in the resting potential.
7. Tetrodotoxin blocks voltage-gated sodium channels and ouabain blocks
sodium-potassium pumps. If you add both to neural tissue, what responses
would you expect?
• A) Immediate loss of resting potential with gradual loss of action potential
• B) Immediate loss of action potential with gradual loss of resting potential
• C) No change to resting or action potentials
• D) Hyperpolarization of the cell membrane
• Correct Answer: B
• Explanation: Blocking sodium channels immediately prevents action
potentials (tetrodotoxin), while blocking the pump slowly degrades the
resting potential gradient over time (ouabain).
8. How could you experimentally increase the magnitude of inhibitory
postsynaptic potentials (IPSPs) generated at a synapse?
• A) Increase Na+ permeability
• B) Increase K+ permeability
• C) Decrease K+ permeability