Question 1

The resting membrane potential of a typical neuron is more negative then the equilibrium potential for potassium.

Accepted Answer

The resting membrane potential of a typical neuron is less negative than the equilibrium potential for potassium due to the influence of other ions, primarily sodium, which makes it less negative than the potassium equilibrium potential.

Question 2

Facilitated diffusion requires energy expenditure.

Accepted Answer

Facilitated diffusion does not require energy expenditure. It uses membrane proteins to move molecules from an area of high concentration to an area of low concentration, following the concentration gradient. It is a passive process that does not require ATP or other forms of energy.

Question 3

The large protein anion does not leave the cell because it cannot easily cross the membrane.

Accepted Answer

Large protein anions cannot diffuse across the cell membrane due to their size and charge. They require specific transport mechanisms such as endocytosis or facilitated diffusion through ion channels or transporters.

Question 4

Movement of K⁺ into the cell requires energy expenditure, whereas movement of Na⁺ into the cell does not.

Accepted Answer

The statement is correct. Movement of K⁺ into the cell requires active transport, which uses energy in the form of ATP. Movement of Na⁺ into the cell, on the other hand, can occur through passive diffusion, which does not require energy expenditure.

Question 5

Potassium movement into cells always requires energy expenditure.

Accepted Answer

Potassium movement into cells requires active transport, which involves the expenditure of energy (usually in the form of ATP). This is necessary because the concentration of potassium ions is typically higher inside cells than outside, so they must be actively transported against the concentration gradient. Without energy expenditure, potassium would simply diffuse out of cells and into the extracellular fluid, leading to disturbances in cell function and potential damage.

Question 6

The sodium-potassium pump indirectly offers the energy source for glucose transport across intestinal cells.

Accepted Answer

The sodium-potassium pump creates a concentration gradient of ions that indirectly provides the energy source for glucose transport across intestinal cells. This is because the concentration gradient created by the pump drives the co-transport of glucose and sodium across the intestinal cell membrane, allowing glucose to be transported against its concentration gradient. Therefore, the sodium-potassium pump indirectly offers the energy source for glucose transport.

Question 7

The model of the plasma membrane as a lipid bilayer studded and penetrated by proteins is known as the ____________________ model of membrane structure.

Accepted Answer

The answer of The model of the plasma membrane as...

Question 8

With active transport, ATP energy is used in the phosphorylation-dephosphorylation cycle of the carrier.

Accepted Answer

Active transport involves the movement of ions or molecules against their concentration gradient, and this process requires energy in the form of ATP. The carrier proteins involved in active transport use ATP energy in the phosphorylation-dephosphorylation cycle to alter their conformation and enable the transport of molecules across the membrane.

Question 9

At resting membrane potential, passive and active forces exactly balance each other so there is no net movement of ions across the membrane.

Accepted Answer

At resting membrane potential, the membrane is in equilibrium with no net movement of ions across the membrane as the passive forces (diffusion) and active forces (membrane pumps) balance each other.

Question 10

Osmosis does not occur if the concentration gradients for water and solutes are absent in a system.

Accepted Answer

Osmosis is the movement of water molecules across a selectively permeable membrane from an area of higher concentration to an area of lower concentration. This movement is driven by the concentration gradient of water. If there are no concentration gradients for water and solutes, osmosis will not occur.

Question 11

At the equilibrium potential for K⁺, the concentration an electrical gradients for K⁺ are in opposition to each other an exactly balance each other so there is no net movement of K⁺.

Accepted Answer

At equilibrium potential, the electrochemical gradient for a particular species is exactly balanced, resulting in no net movement of that species. Therefore, the statement is true.

Question 12

Most of the membrane potential of the plasma membrane is established by the Na⁺-K⁺ pump.

Accepted Answer

The answer of Most of the membrane potential of the...

Question 13

Cations are attracted to a more positively charged area along an electrical gradient.

Accepted Answer

Cations, which are positively charged ions, are attracted to negatively charged areas along an electrical gradient, not positively charged areas.

Question 14

Cations tend to move toward a negatively charged area.

Accepted Answer

This is because cations are positively charged ions, therefore they are attracted to negative charges.

Question 15

The direct actions of the sodium-potassium pump contribute to the majority of the generation of the resting membrane potential.

Accepted Answer

The resting membrane potential is primarily generated by the diffusion of potassium ions through leak channels, not directly by the sodium-potassium pump, which maintains ion gradients.

Question 16

If a concentration or electrical gradient is present for a given substance, the substance will always passively permeate the membrane.

Accepted Answer

Not all substances can passively permeate a membrane even if a gradient exists; permeability depends on the membrane's properties and the substance's characteristics.

Question 17

Net sodium movement into the cell occurs passively, whereas net sodium movement out of the cell occurs actively.

Accepted Answer

This statement is true. Net sodium movement into the cell occurs passively due to the concentration gradient, while net sodium movement out of the cell requires energy and occurs actively through the use of the sodium-potassium pump.

Question 18

The equilibrium potential for a given ion decreases as the difference in concentration of the ion outside and inside the cell increases.

Accepted Answer

The equilibrium potential for an ion is determined by the Nernst equation, which shows that the potential increases with a greater concentration gradient across the membrane.

Question 19

When equilibrium is achieved and no net diffusion is taking place, there is no movement of molecules.

Accepted Answer

Even at equilibrium, molecules continue to move, but there is no net movement in any particular direction.

Question 20

At resting potential, the outside of the cell is negative compared to the intracellular fluid.

Accepted Answer

At resting potential, the outside of the cell is positive compared to the intracellular fluid due to the distribution of ions, particularly sodium and potassium.

Quiz 3: The Plasma Membrane and Membrane Potential