Q: Which of the following best explains why the resting membrane potential (RMP) of most cells is negative?

The plasma membrane is more permeable to K\textsuperscript{+} than Na\textsuperscript{+}, allowing K\textsuperscript{+} to diffuse out, leaving behind negatively charged proteins.

Q: Which of the following is a direct result of the Na\textsuperscript{+}/K\textsuperscript{+} pump activity?

The cell maintains a high concentration of Na\textsuperscript{+} outside and K\textsuperscript{+} inside.

Q: Which of the following would most likely result from a mutation that prevents the Na\textsuperscript{+}/K\textsuperscript{+} pump from functioning?

The cell would accumulate Na\textsuperscript{+} inside and lose K\textsuperscript{+} to the outside, disrupting the resting membrane potential.

Question 1

Which of the following best explains why the resting membrane potential (RMP) of most cells is negative?

Accepted Answer

The plasma membrane is more permeable to K	extsuperscript{+} than Na	extsuperscript{+}, allowing K	extsuperscript{+} to diffuse out, leaving behind negatively charged proteins.

Question 2

A neuron has a resting membrane potential of $$-70\ \mathrm{mV}. If $$the extracellular concentration of K	extsuperscript{+} increases, what is the most likely effect on the membrane potential?

Accepted Answer

It will become less negative (depolarize).

Question 3

Which equation can be used to calculate the equilibrium potential for an ion across a membrane?

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 4

Which of the following is a direct result of the Na	extsuperscript{+}/K	extsuperscript{+} pump activity?

Accepted Answer

The cell maintains a high concentration of Na	extsuperscript{+} outside and K	extsuperscript{+} inside.

Question 5

Which of the following best describes 'contact signaling' between cells?

Accepted Answer

Cells recognize and respond to unique surface membrane receptors on adjacent cells.

Question 6

A ligand binds to a plasma membrane receptor and causes the opening of a chemically gated ion channel. What is the most immediate effect?

Accepted Answer

Ions flow across the membrane, altering the membrane potential.

Question 7

Which of the following is TRUE regarding the effect of acetylcholine on different cell types?

Accepted Answer

Acetylcholine can stimulate contraction in skeletal muscle but inhibit contraction in cardiac muscle.

Question 8

Which of the following is NOT a function of integral proteins in the plasma membrane?

Accepted Answer

Synthesizing DNA for the cell.

Question 9

A cell is exposed to a hormone that binds to its plasma membrane receptor, activating adenylyl cyclase. Which second messenger is most likely to increase?

Accepted Answer

cAMP (cyclic adenosine monophosphate)

Question 10

Which of the following best describes the role of plasma membrane receptors in chemical signaling?

Accepted Answer

They interact with ligands to change cell activity, such as enzyme activation or opening ion channels.

Question 11

If a cell's membrane potential changes from $$-70\ \mathrm{mV} to$$ $$-50\ \mathrm{mV}$$, what has occurred?

Accepted Answer

Depolarization

Question 12

Which of the following would most likely result from a mutation that prevents the Na	extsuperscript{+}/K	extsuperscript{+} pump from functioning?

Accepted Answer

The cell would accumulate Na	extsuperscript{+} inside and lose K	extsuperscript{+} to the outside, disrupting the resting membrane potential.

Question 13

Which of the following is TRUE about the voltage measured across the plasma membrane at rest?

Accepted Answer

It is typically between -50 to -90 mV.

Question 14

Which of the following best describes the separation of charge across the plasma membrane?

Accepted Answer

It creates electrical potential energy that can be used for cellular signaling.

Question 15

A drug blocks all chemically gated ion channels in a neuron. What is the most likely effect?

Accepted Answer

The neuron will be unable to respond to neurotransmitters.

Question 16

Which of the following is a correct statement about ligand-receptor interactions?

Accepted Answer

The same ligand can produce different responses in different cell types.

Question 17

Which of the following is most likely to occur when a neurotransmitter binds to its receptor on the postsynaptic cell?

Accepted Answer

The postsynaptic cell's membrane potential may change due to ion channel opening.

Question 18

Which of the following is NOT a way that plasma membrane receptors can change cell activity?

Accepted Answer

Directly synthesizing ATP from ADP.

Cellular Membrane Potential and Cell-Environment Interactions

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