The Action Potential OS 12.4.2 cfu quiz

What is the resting membrane potential of a typical cell?

• -70 mV

• +30 mV

• 0 mV

• -30 mV

Which ion's movement is primarily responsible for the depolarization phase of the action potential?

• Sodium (Na⁺)

• Potassium (K⁺)

• Calcium (Ca²⁺)

• Chloride (Cl⁻)

What happens to the membrane potential when potassium (K⁺) channels open and K⁺ leaves the cell?

• The membrane potential becomes more negative, moving back toward -70 mV.

• The membrane potential becomes more positive, moving toward +30 mV.

• The membrane potential remains unchanged.

• The membrane potential becomes zero.

Tags

NGSS.HS-LS1-3

Explain why hyperpolarization occurs after repolarization during an action potential.

• Because K⁺ channels are slightly delayed in closing, allowing extra K⁺ to leave the cell.

• Because Na⁺ channels remain open longer than necessary.

• Because the sodium-potassium pump stops working.

• Because the membrane becomes impermeable to all ions.

Which phase of the action potential occurs when the membrane potential becomes more negative than the resting potential?

• Depolarization

• Repolarization

• Hyperpolarization

• Resting potential

What is the typical threshold voltage that must be reached for voltage-gated Na+ channels to open during an action potential?

• -70 mV

• -55 mV

• 0 mV

• +30 mV

Which type of channel opens in response to a neurotransmitter binding to its receptor on the membrane?

• Mechanically gated Na+ channel

• Ligand-gated Na+ channel

• Voltage-gated K+ channel

• Voltage-gated Ca2+ channel

Explain the sequence of events that leads to the initiation of an action potential in a neuron.

• The membrane potential stays at rest until a Na+ channel opens, allowing sodium to enter, causing depolarization, and if threshold is reached, voltage-gated Na+ channels open.

• The membrane potential stays at rest until a K+ channel opens, allowing potassium to enter, causing depolarization, and if threshold is reached, voltage-gated K+ channels open.

• The membrane potential stays at rest until a Ca2+ channel opens, allowing calcium to enter, causing depolarization, and if threshold is reached, voltage-gated Ca2+ channels open.

• The membrane potential stays at rest until a Cl- channel opens, allowing chloride to enter, causing depolarization, and if threshold is reached, voltage-gated Cl- channels open.

A stimulus causes the membrane potential of a neuron to change from -70 mV to -60 mV. Will this result in an action potential? Why or why not?

• Yes, because any depolarization causes an action potential.

• No, because the membrane potential did not reach the threshold of -55 mV.

• Yes, because -60 mV is above the resting potential.

• No, because the membrane potential must reach +30 mV.

Which statement best describes the "all or none" principle of action potentials?

• Action potentials vary in size depending on stimulus strength.

• Action potentials only occur if the threshold is reached, and are always the same size.

• Action potentials can be partially triggered.

• Action potentials only occur with weak stimuli.