Free Practice Quiz Question List

5 Electricity in Biological Systems Online Quiz Questions

Use this free practice quiz with 20 questions to review 5 Electricity in Biological Systems, test your knowledge, and prepare for your next test or exam.

20 questions

True or false

1 point

In biological tissues, electrical current is carried mainly by charged ions moving through fluids, unlike the electron-based conduction in a metal wire.

A
True
B
False

Choose one

1 point

Which quantity is defined as electric force per unit charge at a location?

A
Electric potential energy per unit charge
B
Electric force per unit charge
C
Charge per unit time
D
Current per unit resistance

Fill in the blank

1 point

Membrane potential compares voltage on the of a cell with voltage on the .

Choose one

1 point

Two electrodes detect both a small difference in potential and a larger voltage common to both. What does a differential amplifier primarily do?

A
It converts all ionic currents into electron currents inside the tissue.
B
It measures the absolute potential of each electrode separately and ignores their difference.
C
It measures the difference between two electrode potentials and rejects much common voltage.
D
It directly measures the membrane voltage of every cell beneath the electrodes.

True or false

1 point

A cell's resting membrane potential is generally equal to the Nernst potential of one particular ion.

A
True
B
False

Fill in the blank

1 point

During an action potential, rising sodium permeability allows $Na^+$ to enter, causing . Later, rising potassium permeability allows $K^+$ to leave, helping cause .

Written response

1 point

In the simple membrane circuit model, what is the term for the inverse of resistance used to represent ion-channel pathways?

Choose all

1 point

Select all statements that correctly describe the named bioelectric measurements.

A
ECG electrodes record voltage differences associated with the heart's electrical activity.
B
EEG electrodes on the scalp record voltage fluctuations associated with brain activity.
C
EMG electrodes record electrical activity associated with skeletal muscle.
D
An ECG directly reads the membrane voltage of an individual heart cell.
E
An EEG controls the voltage across a small patch of membrane using a fine electrode.

Written response

1 point

A voltage difference of $40\ \mathrm{mV}$ occurs across a membrane thickness of $4\ \mathrm{nm}$ . Assuming a roughly uniform field, use $E=\Delta V/d$ to find the field magnitude. Enter the value in V/m.

Choose one

1 point

A membrane's capacitance doubles while its resistance stays the same. According to $\tau=RC$ , what happens to its circuit time constant?

A
It is halved.
B
It doubles.
C
It remains unchanged.
D
It becomes four times larger.

Choose all

1 point

Select all statements that accurately describe how cells maintain or use ion gradients across membranes.

A
Ion pumps help maintain concentration differences across the membrane.
B
Ion channels provide routes through which ions can move down their electrochemical gradients.
C
In biological tissue, electrical activity is carried mainly by electrons moving through cells as they do in metal wires.
D
Selective membrane permeability contributes to voltage differences across the membrane.

True or false

1 point

As an action potential travels along an axon, it is regenerated in successive regions rather than simply spreading as a fading voltage change.

A
True
B
False

Choose one

1 point

At the Nernst potential for a single ion species, which condition holds for that ion?

A
The ion's concentration is equal inside and outside the cell.
B
The membrane is impermeable to that ion.
C
The electrical force balances that ion's concentration-driven tendency to diffuse.
D
The membrane potential must equal the resting potential of every cell.

Open ended

1 point

Explain how the simple circuit model represents a cell membrane and how its current-balance equation relates currents to changes in membrane voltage. Include one important limit of the analogy.

Choose one

1 point

Which circuit model best represents the electrical behavior of a cell membrane?

A
A capacitor in parallel with ion-channel conductances
B
A battery in series with a single resistor
C
A single resistor with no charge separation
D
An inductor in parallel with a voltage source

Written response

1 point

At what condition is a single ion at its Nernst potential, where the electrical force balances its concentration-driven tendency to diffuse?

Choose one

1 point

During a typical neuronal action potential, which sequence of ion movements best describes depolarization followed by repolarization?

A
K⁺ enters during the rising phase, then Na⁺ leaves to repolarize the membrane.
B
Na⁺ enters during the rising phase, then K⁺ leaves to help repolarize the membrane.
C
Cl⁻ leaves during the rising phase, then Ca²⁺ enters to repolarize the membrane.
D
Na⁺ and K⁺ both leave during the rising phase, then both enter to repolarize the membrane.

Choose one

1 point

Why does an action potential in a myelinated axon appear to jump from one region to the next?

A
The action potential fades continuously beneath the myelin and is restored only at the nerve terminal.
B
The signal travels through myelin as ions flow freely across the insulated membrane.
C
The action potential is regenerated mainly at gaps in the myelin called nodes of Ranvier.
D
The signal is regenerated only at the cell body, then passively spreads down the axon.

Choose one

1 point

A surface bioelectric instrument uses a differential amplifier and has high input impedance. What do these features help it do?

A
It measures the difference between electrode potentials, while high input impedance limits current drawn from the tissue.
B
It measures the sum of electrode potentials, while high input impedance increases current drawn from the tissue.
C
It measures an individual cell's membrane voltage directly, while high input impedance removes all electrical interference.
D
It measures current through a membrane patch, while high input impedance forces ions through the electrodes.

Written response

1 point

A voltage difference of $60\,\mathrm{mV}$ occurs across a membrane thickness of $3\,\mathrm{nm}$ . Using $E=\Delta V/d$ , calculate the approximate field magnitude in MV/m.