Question 1

In the Na⁺/glucose cotransporter, _________ moving down its gradient drives the transport of __________ against its gradient. A)Na⁺ ions, K⁺ ions B)Na⁺ ions, glucose C)glucose, Na⁺ ions D)glucose, K⁺ ions E)K⁺ ions, glucose

Accepted Answer

The Na⁺ ions, which are moving down their concentration gradient, provide the energy necessary to transport glucose against its concentration gradient. Therefore, choice B is the correct answer.

Question 2

What is the distinguishing characteristic of a P-type pump?
A)It must be pumped during the cycle.
B)It must be phosphorylated during the cycle.
C)It must be protonated during the cycle.
D)It must be methylated during the cycle.
E)It must be acetylated during the cycle.

Accepted Answer

P-type pumps are a group of ATPases that are phosphorylated during the transport cycle, which is their distinguishing characteristic.

Question 3

How do Na⁺ ions enter a neuron when an action potential is initiated? A)the Na⁺/K⁺-ATPase B)a gated Na⁺ pump C)a voltage-gated Na⁺ channel D)the ligand-gated Na⁺ channel E)a voltage-gated Na⁺ facilitated transporter

Accepted Answer

During an action potential, the depolarization of the neuron's membrane potential triggers the opening of voltage-gated Na⁺ channels. This allows Na⁺ ions to enter the neuron and cause further depolarization, ultimately leading to the propagation of the action potential down the axon.

Question 4

Where in a myelinated axon are nearly all of the ion channels concentrated?
A)the cell body
B)nodes of Ranvier
C)dendrites
D)axon terminals
E)neuron nucleus

Accepted Answer

Ion channels are concentrated at the nodes of Ranvier, where there is a gap in the myelin sheath. This allows for the action potential to be regenerated and propagated along the axon.

Question 5

What causes the membrane potential to return to the normal negative value after an action potential has occurred? A)opening of a voltage-gated K⁺ channel B)opening of a voltage-gated Na⁺ channel C)closing of a voltage-gated K⁺ channel D)opening of a ligand-gated Na⁺ channel E)opening of a voltage-gated K⁺ facilitated transporter

Accepted Answer

The opening of voltage-gated potassium (K+) channels allows K+ to flow out of the neuron, which helps to restore the negative membrane potential after an action potential.

Question 6

What is caused by the inability of Na⁺ ion channels to open for several milliseconds after their inactivation? A)hyperpolarization B)depolarization C)termination D)a refractory period E)an action potential

Accepted Answer

The inability of Na⁺ ion channels to open for several milliseconds after their inactivation causes a refractory period, during which the neuron cannot generate another action potential. This period ensures that the action potential moves in one direction only, from the dendrites to the axon terminal.

Question 7

How is a nerve impulse usually transmitted across a synapse from a presynaptic to a postsynaptic cell? A)via a direct connection B)via a spark C)via a neurotransmitter D)via Na⁺ ions E)via plasmodesmata

Accepted Answer

A nerve impulse is transmitted across a synapse through the release of neurotransmitters from the presynaptic cell into the synaptic cleft, which then bind to receptors on the postsynaptic cell and trigger a response.

Question 8

Where is the neuron cell nucleus located?
A)axon hillock
B)cell body
C)dendrites
D)axon
E)terminal knob

Accepted Answer

The neuron cell nucleus is located in the cell body.

Question 9

Which disease is caused by the deterioration of the myelin sheath?
A)myasthenia gravis
B)multiple sclerosis
C)muscular dystrophy
D)diabetes mellitus
E)lupus erythematosus

Accepted Answer

Multiple sclerosis is caused by the deterioration of the myelin sheath, which is the protective covering around nerve fibers in the central nervous system. This can result in a range of symptoms including muscle weakness, balance and coordination problems, and cognitive difficulties. Myasthenia gravis is a neuromuscular disorder, muscular dystrophy is a genetic disorder that affects muscle development and function, diabetes mellitus is a metabolic disorder that affects blood sugar regulation, and lupus erythematosus is an autoimmune disease that can affect multiple organs and systems in the body.

Question 10

Diffusion during which the substance to be transported binds selectively to a membrane-spanning protein, which helps the process along, is called ________.
A)osmosis
B)facilitated osmosis
C)simple diffusion
D)facilitated diffusion
E)active transport

Accepted Answer

The definition given describes facilitated diffusion, which involves the use of a membrane protein to help transport the substance across the membrane. Osmosis, simple diffusion, and active transport do not involve membrane-spanning proteins for transport. Facilitated osmosis is not a commonly used term in biology.

Question 11

Impulse propagation by a myelinated axon is called ____________ conduction.
A)saltatory
B)myelinated
C)rapid fire
D)jump stop
E)leap frog

Accepted Answer

Saltatory conduction is the process by which nerve impulses jump from one node of Ranvier to the next in a myelinated axon, speeding up the transmission of the impulses.

Question 12

An important aspect of transport by facilitated transporters and pumps is ________.
A)conformational shifts
B)rigidity
C)softness
D)$\alpha$-helix secondary structure
E)$\beta$-pleated sheet secondary structure

Accepted Answer

Facilitated transporters and pumps undergo conformational shifts to transport molecules across a membrane. These shifts allow for ligand binding and changes in protein shape that move the molecule from one side of the membrane to the other. Rigidity or softness of the transporter would not allow for this movement, and the F1F1F1S1F1F1F10-helix and F1F1F1S1F1F1F10-pleated sheet structures are not relevant to facilitated transport or pumps.

Question 13

The sodium-potassium pump makes the cell interior more _________ by pumping _______ sodium ions out of the cell for every ___________ potassium ions pumped in.
A)negative, 3, 2
B)negative, 2, 3
C)positive, 3, 2
D)positive, 2, 3
E)negative, 4, 3

Accepted Answer

The sodium-potassium pump contributes to the cell's negative interior by actively transporting 3 sodium ions out of the cell and 2 potassium ions into the cell, using ATP for energy. This results in a higher concentration of positive ions outside the cell compared to inside, thus maintaining the negative charge of the cell interior.

Question 14

What happens after a subthreshold depolarization?
A)a full action potential
B)a partial action potential
C)no action potential
D)a proportional action potential
E)a reversal of the direction of the neural impulse

Accepted Answer

A subthreshold depolarization does not reach the threshold potential required to initiate an action potential. Therefore, there will be no action potential generated.

Question 15

Which site in a neuron receives incoming information from external sources?
A)Dendrites
B)Axon
C)Axon hillock
D)Terminal knob
E)Cell body

Accepted Answer

Dendrites are the site in a neuron that receives incoming information from external sources. They are typically highly branched and extend from the cell body, acting as the main site for synapse formation with other neurons or sensory receptors.

Question 16

A transport system that moves one solute into the cell and another one out of the cell during a single cycle accompanied by the expenditure of energy through ATP hydrolysis could be called _______
A)an active antiport
B)an active uniport
C)a passive antiport
D)an active symport
E)a passive symport

Accepted Answer

This transport system is described as moving solutes in opposite directions (one in and one out of the cell) and requiring the expenditure of energy through ATP hydrolysis, which is characteristic of active transport. "Antiport" refers to the movement of solutes in opposite directions, and "symport" refers to the movement of solutes in the same direction. Therefore, the best choice is A, active antiport.

Question 17

The ability, possessed by all organisms, to respond to external stimulation is known as _______.
A)excitation
B)irritability
C)irritation
D)irrigation
E)receptiveness

Accepted Answer

The ability to respond to external stimulation is commonly referred to as irritability, as organisms can become irritated by certain stimuli and respond accordingly. Choice A (excitation) is similar but refers more to the state of being excited or stimulated rather than the ability to respond. Choice C (irritation) is also similar, but refers more to a negative emotional or physical response to a stimulus rather than the ability to respond. Choice D (irrigation) refers to the process of watering crops or land, and choice E (receptiveness) refers more to the willingness to receive or accept something rather than the ability to respond to external stimuli.

Question 18

As an action potential is initiated, the membrane is __________. This is caused by the ________ of ________ ions. A)hyperpolarized, efflux, Na⁺ B)depolarized, influx, Na⁺ C)depolarized, influx, K⁺ D)hyperpolarized, influx, Na⁺ E)depolarized, efflux, Na⁺

Accepted Answer

As an action potential is initiated, the membrane is depolarized. This is caused by the influx of Na+ ions.

Question 19

Which part of a neuron conducts impulses away from the cell body toward the target cell(s)?
A)axon hillock
B)cell body
C)dendrites
D)axon
E)terminal knob

Accepted Answer

The axon is the part of a neuron that conducts impulses away from the cell body toward the target cell(s). It is often referred to as the "nerve fiber."

Question 20

What is thought to cause the 1 ms inactive time after a sodium channel initiates an action potential?
A)a higher positive charge
B)a higher negative charge
C)the presence of an inactivating peptide in the opening of the channel pore
D)removal of a peptide from the channel protein
E)covalent addition of a peptide to the cytoplasmic end of the channel protein

Accepted Answer

The presence of an inactivating peptide in the opening of the channel pore is thought to cause the 1 ms inactive time after a sodium channel initiates an action potential. This peptide blocks the pore, preventing the flow of sodium ions, until it is released after a brief period of time.

Quiz 4: The Structure and Function of the Plasma Membrane

In the Na⁺/glucose cotransporter, _ moving down its gradient drives the transport of __ against its gradient.

What is the distinguishing characteristic of a P-type pump?

How do Na⁺ ions enter a neuron when an action potential is initiated?

Where in a myelinated axon are nearly all of the ion channels concentrated?

What causes the membrane potential to return to the normal negative value after an action potential has occurred?

What is caused by the inability of Na⁺ ion channels to open for several milliseconds after their inactivation?

How is a nerve impulse usually transmitted across a synapse from a presynaptic to a postsynaptic cell?

Where is the neuron cell nucleus located?

Which disease is caused by the deterioration of the myelin sheath?

Diffusion during which the substance to be transported binds selectively to a membrane-spanning protein, which helps the process along, is called ________.

Impulse propagation by a myelinated axon is called ____________ conduction.

An important aspect of transport by facilitated transporters and pumps is ________.

The sodium-potassium pump makes the cell interior more _____ by pumping _ sodium ions out of the cell for every _________ potassium ions pumped in.

What happens after a subthreshold depolarization?

Which site in a neuron receives incoming information from external sources?

A transport system that moves one solute into the cell and another one out of the cell during a single cycle accompanied by the expenditure of energy through ATP hydrolysis could be called _______

The ability, possessed by all organisms, to respond to external stimulation is known as _______.

As an action potential is initiated, the membrane is __. This is caused by the of ions.

Which part of a neuron conducts impulses away from the cell body toward the target cell(s) ?

What is thought to cause the 1 ms inactive time after a sodium channel initiates an action potential?