Chapter 12

Question 0

Although the extracellular enviroemt has a high sodium ink concentration and the intracellular environment has a high potassium ion concentration, both must be neutralized by negatively charged molecules. In the extracellular case, what is the principle anion?

1. HCO3-
2. Cl-
3. PO4^3-
4. OH-

Answer 0

Cl-

Question 1

Which if the following channels would not be expected to generate a change in voltage by movement of it’s substrate across the membrane where it is found?

1. An aquaporin
2. A sodium channel
3. A calcium channel
4. A proton channel

Answer 1

An aquaporin

Question 2

Which of the following has the lowest rate of diffusion across an artificial membrane?

1. Glucose
2. Water
3. Glycerol
4. Ethanol

Answer 2

Glucose

Question 3

Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant outside a typical mammalian cell?

1. Na+
2. K+
3. Ca^2+
4. Cl-

Answer 3

Na+

Question 4

Which of the following ions is the most abundant inside a typical mammalian cell?

1. Na+
2. K+
3. Ca^2+
4. Cl-

Answer 4

K+

Question 5

Which of the following negatively charged ions is NOT primarily used to buffer positive charges inside the cell?

1. PO4^3-
2. OH-
3. Cl-
4. HCO3-

Answer 5

Cl-

Question 6

Which of the following negatively charged ions is the most abundant outside the cell and which ion does most often neutralize?

1. Cl- (Ca2+)
2. PO4^3- (K+)
3. PO4^3- (Ca2+)
4. Cl- (Na+)

Answer 6

Cl- (Na+)

Question 7

Which of the following statements about resting membrane potential is NOT true?

1. The resting membrane potential for most animal cells is 0 mV, because the positive and negative ions are in balance.
2. The resting membrane potential for most animal cells is positive, because Na+ ions are so plentiful inside cells.
3. The resting membrane potential for most animal cells is negative, because the inside of the cell is more negatively charged than the outside of the cell.
4. At the resting membrane potential, no ions enter or exit the cell.

Answer 7

3.

Question 8

A hungry yeast cell lands in a car of grape juice and begins to feast on the sugars there, producing carbon dioxide and ethanol in the process. Unfortunately, the grape juice is contaminated with professes that attack some of the transport proteins in the yeast cell membrane, and the yeast cell died. Which of the following could account for the yeast cells demise?

1. Toxic buildup of carbon dioxide inside the cell
2. Toxic buildup of ethanol inside the cell
3. Diffusion of ATP out of the cell
4. Inability to import sugar into the cell

Answer 8

Inability to import sugar into the cell

Question 9

Ion channels are classified as membrane transport proteins. Channels discriminate by size and charge. In addition to Na+, which of the following ions would you expect to be able to freely diffuse through a Na+ channel?

1. Mg2+
2. H+
3. K+
4. Cl-

Answer 9

H+

Question 10

Some cells have aquaporins—channels that facilitate the flow of water molecules through the plasma membrane. For these cells, what regulates the rate and direction of water diffusion across the membrane?

1. Aquaporin conformation
2. Resting montane potential
3. Solute concentrations on either side of the membrane
4. Availability of ATP

Answer 10

Solute concentrations on either side of the membrane

Question 11

Transporters, in contrast to channels, work by ______.

1. Specific binding to solutes
2. A gating mechanism
3. Filtering solutes by charge
4. Filtering solutes by size

Answer 11

Specific binding to solutes

Question 12

Pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across the membranes, against their concentration gradient. This type of transport is called ______.

1. Active transport
2. Free diffusion
3. Facilitated diffusion
4. Passive transport

Answer 12

Active transport

Question 13

Active transport requires the input of energy into a system so as to move solutes against their electrochemical and concentration gradients. Which if the following is NOT one of the common ways to perform active transport?

1. Na+-coupled
2. K+ - coupled
3. ATP - driven
4. Light-driven

Answer 13

K+ - coupled

Question 14

The Na+ - K+ ATPase is also known as the Na+ - K+ pump. It is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration. What happens immediately after the pump hydroxides ATP?

1. Na+ is bound
2. ADP is bound
3. The pump is phosphorylated
4. The pump changes conformation

Answer 14

The pump is phosphorylated

Question 15

You have generated antibodies that recognize the extracellular domain of the Ca2+ pump. Adding these antibodies to animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment. What do you expect to observe with respect to intracellular Ca2+?

1. Ca2+ pumps in vesicle membranes keep cytosolic calcium levels low.
2. Ca2+ pumps in the Endoplasmic reticulum membrane keep Cyrillic calcium levels low.
3. Ca2+ pumps on the Golgi apparatus keep cytosolic calcium levels low
4. Ca2+ concentrations in the cytosol increase at a steady rate

Answer 15

Ca2+ pumps in the Endoplasmic reticulum membrane keep cytosolic calcium levels low.

Question 16

Which of the following proton transporters is used to regulate pH in animal cells?

1. Light driven pump
2. H+ ATPase
3. H+ symporter
4. Na+ - H+ exchanger

Answer 16

Na+ - H+ exchanger

Question 17

Which of the following statements is true?

1. Amoebae have transporter proteins that actively pump water molecules from the cytoplasm to the cell exterior.
2. Bacteria and animal cells rely on the Na+ - K+ pump in the plasma membrane to prevent lysis resulting from osmotic imbalances.
3. The Na+ - K+ pump allows animal cells to thrive under conditions of very low iconic strength.
4. The Na+ - K+ pump helps to keep both Na + and Cl- ions out of the cell.

Answer 17

The Na+ - K+ pump helps to keep both Na+ and Cl - ions out of the cell

Question 18

Ca2+ pumps in the plasma membrane and Endoplasmic reticulum are important for ______.

1. Maintaining osmotic balance
2. Preventing Ca2+ from altering the activity of molecules in the cytosol
3. Providing enzymes in the Endoplasmic reticulum with Ca2+ ions that are necessary for their catalytic activity.
4. Maintaining a negative membrane potential.

Answer 18

Preventing Ca2+ from altering the activity of molecules in the cytosol

Question 19

Which of the following occur without coupling transport of the solute to the movement of a second solute?

1. Import of glucose into gut epithelial cells.
2. Export of Ca2+ from the cytosol
3. Export of H+ from animal cells for pH regulation.
4. The export of Na+ from cells to maintain resting membrane potential

Answer 19

Export of Ca2+ from the cytosol

Question 20

Which of the following best describes the behavior of a gated channel?

1. It stays open continuously when stimulated
2. It opens more frequently in response to a given stimulus
3. It opens more widely as the stimulus becomes stronger
4. It remains closed if unstimulated

Answer 20

It opens more frequently in response to a given stimulus

Question 21

The stimulation of auditory nerves depends on the opening and closing of channels in the auditory hair cells. Which type of gating mechanism do these cells use?

1. Voltage-gated
2. Extracellular ligand gated
3. Intracellular ligand gated
4. Stress gated

Answer 21

Stress gated

Question 22

Voltage gated channels contain charged protein domains, which are sensitive to changes in membrane potential. By responding to a threshold In the membrane potential, these voltage sensors trigger the opening of the channels. Which of the following best describes the behavior of a population of channels exposed to such a threshold.

1. Some channels remain closed and some open completely.
2. All channels open completely
3. All channels open partly to the same degree
4. All channels open partly each to a different degree

Answer 22

Some channels remain closed and done open completely

Question 23

When the net charge on either side of the plasma membrane is zero, what else is true?

1. There is an equal number of K+ ions on each side of the plasma membrane
2. The K+ leak channels are open
3. The electrochemical potential across the membrane is zero
4. The resting membrane potential is between -20 mV and -200 mV

Answer 23

The electrochemical potential across the membrane is zero

Question 24

K+ leak channels are found in the plasma membrane. These channels open and close in an unregulated, random fashion. What do they accomplish in a resting cell? 1. They set the K+ concentration gradient to zero 2. They set the membrane potential to zero 3. They disrupt the resting membrane potential 4. They keep the electrochemical gradient for K+ at zero

Answer 24

They keep the electrochemical gradient for K+ at zero

Question 25

The Nernst equation can be used to calculate the membrane potential bass on the ratio of the outer and inner ion concentration. In a resting cell, membrane potential is calculated taking only K+ ions into account. What is V when Co = 15 mM and Ci = 106 mM? 1. 438.1 mV 2. -52.7 mV 3. 52.7 4. -5.3 mV

Answer 25

-52.7 mV

Question 26

When using the Nernst equation to calculate membrane potential, we are making several assumptions about conditions in the cell. Which of the following is not a good assumption? 1. The temperature is 37 degrees Celsius 2. The plasma membrane is primarily permeable to Na+ 3. At rest the interior of a cell is more negatively charged than the exterior. 4. K+ is the principle positive ion in the cell

Answer 26

The plasma membrane is primarily permeable to Na+

Question 27

If Na+ channels are opened in a cell that was previously at rest, how will the resting membrane potential be affected? 1. The membrane potential is not affected by Na+ 2. It becomes more negative 3. It becomes more positive 4. It is permanently reset

Answer 27

It becomes more positive

Question 28

Which of the following statements does not accurately describe the events involved in the propagation of an action potential? 1. An initial influx of Na+ through a small cluster of channels causes local depolarization of the membrane 2. Local depolarization causes nearby Na+ channels to open 3. Channels in depolarized regions of the membrane are inactivated until the resting membrane potential is reestablished. 4. The opening of transmitter gated K+ channels helps to repolarize the membrane.

Answer 28

The opening of transmitter gated K+ channels helps to repolarize the membrane

Question 29

Which of the following is required for the secretion of neurotransmitters I'm response to an action potential? 1. Neurotransmitter receptors 2. Na+ - K+ pumps 3. Voltage-gated K+ channels 4. Voltage gated Ca2+ channels

Answer 29

Voltage gated Ca2+ channels

Question 30

The stimulation of a motor neuron ultimately results in the release of a neurotransmitter at the synapse between the neuron and a muscle cell. What type of neurotransmitter is used at these neuromuscular junctions? 1. Acetylcholine 2. Glutamate 3. GABA 4. Glycine

Answer 30

Acetylcholine

Question 31

Both excitatory and inhibitory neurons form junctions with muscles. By what mechanism do inhibitory neurotransmitters prevent the post synaptic cell from firing an action potential? 1. By closing Na+ channels 2. By preventing the secretion of excitatory neurotransmitters 3. By opening K+ channels 4. By opening Cl- channels

Answer 31

By opening Cl- channels

Question 32

Which of the following statements best reflects the nature of synaptic plasticity? 1. New synapses are created due to the postnatal generation of neurons 2. Synaptic response changes in magnitude depending on frequency of stimulation 3. There is a change I'm the type of neurotransmitter used at the synapse 4. Neuronal connections are pruned during normal development.

Answer 32

Synaptic response changes in magnitude depending on frequency of stimulation.

Question 33

Approximately, how many distinct synapses are established on the dendrites and cell body of a motor neuron in the spinal cord? 1. Tens 2. Hundreds 3. Thousands 4. Millions

Answer 33

Thousands

Question 34

Which of the following statements about GABA receptors is not true? 1. They are located on postsynaptic membranes 2. They are ligand gated channels 3. They inhibit synaptic signaling 4. They promote neural uptake of Na+

Answer 34

Thy promote neural uptake of Na+

Question 35

Which of the following gated ion channels are involved in inhibitory synaptic signaling? 1. Voltage gated Na+ channels 2. Voltage gated Ca2+ channels 3. Glycine gated Cl- channels 4. Glutamate gated cation channels

Answer 35

Glycine gated Cl- channels