Steps 7 and 10 of glycolysis result in substrate-level phosphorylation. Which of the following best describes this process?

Steps 7 and 10 of glycolysis result in substrate-level phosphorylation. Which of the following best describes this process?

(a) ATP is being hydrolyzed to phosphorylate the substrate.
(b) The energy derived from substrate oxidation is coupled to the conversion of ADP to ATP.
(c) Two successive phosphates are transferred, first to AMP, then to ADP, finally forming ATP.
(d) The substrate is hydrolyzed using ATP as an energy source.

Answer: 

The conversion of glyceraldehyde 3-phosphate to 1,3 bisphosphoglycerate in step 6 of glycolysis generates a "high energy" phosphoanhydride bond. Which of the following best describes what happens to that bond in step 7?

The conversion of glyceraldehyde 3-phosphate to 1,3 bisphosphoglycerate in step 6 of glycolysis generates a "high energy" phosphoanhydride bond. Which of the following best describes what happens to that bond in step 7? 

(a) It is hydrolyzed to drive the formation of ATP.
(b) It is hydrolyzed to drive the formation of NADH.
(c) It is hydrolyzed to generate pyruvate.
(d) It is oxidized to CO2.

Answer: 

In step 4 of glycolysis, a six-carbon sugar (fructose 1,6-bisphosphate) is cleaved to produce two three-carbon molecules (dihydroxyacetone phosphate and glyceraldehyde 3-phosphate). Which enzyme catalyzes this reaction?

In step 4 of glycolysis, a six-carbon sugar (fructose 1,6-bisphosphate) is cleaved to produce two three-carbon molecules (dihydroxyacetone phosphate and glyceraldehyde 3-phosphate). Which enzyme catalyzes this reaction?

(a) aldolase
(b) phosphoglucose isomerase
(c) enolase
(d) triose phosphate isomerase

Answer: 

Which of the following steps or processes in aerobic respiration include the production of carbon dioxide?

Which of the following steps or processes in aerobic respiration include the production of carbon dioxide?

(a) breakdown of glycogen
(b) glycolysis
(c) conversion of pyruvate to acetyl CoA
(d) oxidative phosphorylation

Answer: 

Glycolysis generates more stored energy than it expends. What is the net number of activated carrier molecules produced in this process (number and type of molecules produced minus the number of those molecules used as input)?

Glycolysis generates more stored energy than it expends. What is the net number of activated carrier molecules produced in this process (number and type of molecules produced minus the number of those molecules used as input)?

(a) 6 ATP, 2 NADH
(b) 4 ATP, 4 NADH
(c) 2 ATP, 2 NADH
(d) 4 ATP, 2 NADH

Answer: 

The final metabolite produced by glycolysis is ___________.

The final metabolite produced by glycolysis is ___________.

(a) acetyl CoA.
(b) pyruvate.
(c) 3-phosphoglycerate.
(d) glyceraldehyde 3-phosphate.

Answer: 

Foods are broken down into simple molecular subunits for distribution and use throughout the body. Which type of simple subunits, listed below, is used preferentially as an energy source?

Foods are broken down into simple molecular subunits for distribution and use throughout the body. Which type of simple subunits, listed below, is used preferentially as an energy source?

(a) simple sugars
(b) proteins
(c) free fatty acids
(d) glycerol

Answer: 

The advantage to the cell of the gradual oxidation of glucose during cellular respiration compared with its combustion to CO2 and H2O in a single step is that ________________.

The advantage to the cell of the gradual oxidation of glucose during cellular respiration compared with its combustion to CO2 and H2O in a single step is that ________________.

(a) more free energy is released for a given amount of glucose oxidized.
(b) no energy is lost as heat.
(c) energy can be extracted in usable amounts.
(d) more CO2 is produced for a given amount of glucose oxidized.

Answer: 

Which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP?

Which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP?

(a) the digestion of starch to glucose
(b) glycolysis
(c) the citric acid cycle
(d) oxidative phosphorylation


Answer: 

Glycolysis is an anaerobic process used to catabolize glucose. What does it mean for this process to be anaerobic?

Glycolysis is an anaerobic process used to catabolize glucose. What does it mean for this process to be anaerobic?

(a) no oxygen is required
(b) no oxidation occurs
(c) it takes place in the lysosome
(d) glucose is broken down by the addition of electrons

Answer: 

Which of the following gated ion channels are involved in inhibitory synaptic signaling?

Which of the following gated ion channels are involved in inhibitory synaptic signaling?

(a) voltage-gated Na+ channels
(b) voltage-gated Ca2+ channels
(c) glycine-gated Cl- channels
(d) glutamate-gated cation channels

Answer: 

Which of the following statements about GABA receptors is not true?

Which of the following statements about GABA receptors is not true?

(a) They are located on postsynaptic membranes.
(b) They are ligand-gated channels.
(c) They inhibit synaptic signaling.
(d) They promote neuronal uptake of Na+.



Answer: 

Approximately, how many distinct synapses are established on the dendrites and cell body of a motor neuron in the spinal cord?

Approximately, how many distinct synapses are established on the dendrites and cell body of a motor neuron in the spinal cord?

(a) tens
(b) hundreds
(c) thousands
(d) millions


Answer: 

Which of the following statements best reflects the nature of synaptic plasticity?

Which of the following statements best reflects the nature of synaptic plasticity?

(a) New synapses are created due to the postnatal generation of neurons.
(b) Synaptic response changes in magnitude depending on frequency of stimulation.
(c) There is a change in the type of neurotransmitter used at the synapse.
(d) Neuronal connections are pruned during normal development.

Answer: 

Which of the following statements does not accurately describe the events involved in the propagation of an action potential?

Which of the following statements does not accurately describe the events involved in the propagation of an action potential?

(a) An initial influx of Na+ through a small cluster of channels causes local depolarization of the membrane.
(b) Local depolarization causes nearby Na+ channels to open.
(c) Channels in depolarized regions of the membrane are inactivated until the resting membrane potential is reestablished.
(d) The opening of transmitter-gated K+ channels helps to repolarize the membrane.

Answer: 

In a method called patch-clamping, a glass capillary can be converted into a microelectrode that measures the electrical currents across biological membranes. Which of the following is not true about the patch-clamp method?

In a method called patch-clamping, a glass capillary can be converted into a microelectrode that measures the electrical currents across biological membranes. Which of the following is not true about the patch-clamp method?

(a) The glass capillary adheres to a "patch" of membrane through the application of suction.
(b) The aperture in the glass capillary used to make a microelectrode is about 1 µm in diameter.
(c) If the experimental conditions are held constant, fluctuations in electrical currents across the patch of membrane are still observed.
(d) Single-channel patch-clamp recordings have demonstrated that gated membrane channels will only open and close in response to specific stimuli.

Answer: 

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

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

(a) There is an equal number of K+ ions on each side of the plasma membrane.
(b) The K+ leak channels are open.
(c) The electrochemical potential across the membrane is zero.
(d) The resting membrane potential is between -20 mV and -200 mV.


Answer: 

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

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

(a) import of glucose into gut epithelial cells
(b) export of Ca2+ from the cytosol
(c) export of H+ from animal cells for pH regulation
(d) the export of Na+ from cells to maintain resting membrane potential

Answer: 

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?

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?

(a) aquaporin conformation
(b) resting membrane potential
(c) solute concentrations on either side of the membrane
(d) availability of ATP



Answer: 

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

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

(a) The resting membrane potential for most animal cells is 0 mV, because the positive and negative ions are in balance.
(b) The resting membrane potential for most animal cells is positive, because Na+ ions are so plentiful inside cells.
(c) 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.
(d) At the resting membrane potential, no ions enter or exit the cell.

Answer: 

Negatively charged ions are required to balance the net positive charge from metal ions such as K+, Na+, and Ca2+. Which of the following negatively charged ions is the most abundant outside the cell and which ion does most often neutralize (written in parentheses)?

Negatively charged ions are required to balance the net positive charge from metal ions such as K+, Na+, and Ca2+. Which of the following negatively charged ions is the most abundant outside the cell and which ion does most often neutralize (written in parentheses)?

(a) Cl- (Ca2+)
(b) PO43- (K+)
(c) PO43- (Ca2+)
(d) Cl- (Na+)

Answer: 

Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following negatively charged ions is not primarily used to buffer positive charges inside the cell?

Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following negatively charged ions is not primarily used to buffer positive charges inside the cell?

(a) PO43-
(b) OH-
(c) Cl-
(d) HCO3-

Answer: 

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?

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?

(a) Na+
(b) K+
(c) Ca2+
(d) Cl-



Answer: 

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 inside a typical mammalian cell?

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 inside a typical mammalian cell?

(a) Na+
(b) K+
(c) Ca2+
(d) Cl-

Answer: 

Below is a list of molecules with different chemical characteristics. Knowing that all molecules will eventually diffuse across a phospholipid bilayer, select the option below that most accurately predicts the relative rates of diffusion of these molecules (fastest to slowest).

Below is a list of molecules with different chemical characteristics. Knowing that all molecules will eventually diffuse across a phospholipid bilayer, select the option below that most accurately predicts the relative rates of diffusion of these molecules (fastest to slowest).

alanine estrogen propanol sodium



(a) alanine > propanol > sodium > estrogen
(b) sodium > propanol > alanine > estrogen
(c) estrogen > propanol > sodium > alanine
(d) estrogen > propanol > alanine > sodium


Answer: 

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

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

(a) an aquaporin
(b) a sodium channel
(c) a calcium channel
(d) a proton channel

Answer: 

Both excitatory and inhibitory neurons form junctions with muscles. By what mechanism do inhibitory neurotransmitters prevent the postsynaptic cell from firing an action potential?

Both excitatory and inhibitory neurons form junctions with muscles. By what mechanism do inhibitory neurotransmitters prevent the postsynaptic cell from firing an action potential?

(a) by closing Na+ channels
(b) by preventing the secretion of excitatory neurotransmitters
(c) by opening K+ channels
(d) by opening Cl- channels


Answer: 

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?

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?

(a) acetylcholine
(b) glutamate
(c) GABA
(d) glycine

Answer: 

Which of the following is required for the secretion of neurotransmitters in response to an action potential?

Which of the following is required for the secretion of neurotransmitters in response to an action potential?

(a) neurotransmitter receptors
(b) Na+-K+ pumps
(c) voltage-gated K+ channels
(d) voltage-gated Ca2+ channels

Answer: 

If Na+ channels are opened in a cell that was previously at rest, how will the resting membrane potential be affected?

If Na+ channels are opened in a cell that was previously at rest, how will the resting membrane potential be affected?

(a) The membrane potential is not affected by Na+.
(b) It becomes more negative.
(c) It becomes more positive.
(d) It is permanently reset.

Answer: 

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?

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?

(a) The temperature is 37°C.
(b) The plasma membrane is primarily permeable to Na+.
(c) At rest, the interior of the cell is more negatively charged than the exterior.
(d) K+ is the principal positive ion in the cell.

Answer: 

The Nernst equation can be used to calculate the membrane potential based 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?

The Nernst equation can be used to calculate the membrane potential based 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?

(a) 438.1 mV
(b) -52.7 mV
(c) 52.7 mV
(d) -5.3 mV



Answer: 

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?

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?

(a) They set the K+ concentration gradient to zero.
(b) They set the membrane potential to zero.
(c) They disrupt the resting membrane potential.
(d) They keep the electrochemical gradient for K+ at zero.

Answer: 

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?

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?

(a) Some channels remain closed and some open completely.
(b) All channels open completely.
(c) All channels open partly, to the same degree.
(d) All channels open partly, each to a different degree.

Answer: 

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?

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?

(a) voltage-gated
(b) extracellular ligand-gated
(c) intracellular ligand-gated
(d) stress-gated



Answer: 

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

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

(a) It stays open continuously when stimulated.
(b) It opens more frequently in response to a given stimulus.
(c) It opens more widely as the stimulus becomes stronger.
(d) It remains closed if unstimulated.


Answer: 

Ca2+ pumps in the plasma membrane and endoplasmic reticulum are important for _____________.

Ca2+ pumps in the plasma membrane and endoplasmic reticulum are important for _____________.

(a) maintaining osmotic balance
(b) preventing Ca2+ from altering the activity of molecules in the cytosol
(c) providing enzymes in the endoplasmic reticulum with Ca2+ ions that are necessary for their catalytic activity
(d) maintaining a negative membrane potential

Answer: 

Which of the following statements is true?

Which of the following statements is true?

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

Answer: 

Cells make use of H+ electrochemical gradients in many ways. Which of the following proton transporters is used to regulate pH in animal cells?

Cells make use of H+ electrochemical gradients in many ways. Which of the following proton transporters is used to regulate pH in animal cells?

(a) light-driven pump
(b) H+ ATPase
(c) H+ symporter
(d) Na+-H+ exchanger

Answer: 

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+?

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+?

(a) Ca2+ pumps in vesicles membranes keep cystosolic calcium levels low.
(b) Ca2+ pumps in the ER membrane keep cystosolic calcium levels low.
(c) Ca2+ pumps in the Golgi apparatus keep cystosolic calcium levels low.
(d) Ca2+ concentrations in the cytosol increase at a steady rate.

Answer: 

The Aero Schmidt weed contains an ATP-driven ion pump in its vacuolar membrane that pumps potentially toxic heavy metal ions such as Zn2+ and Pb2+ into the vacuole.

The Aero Schmidt weed contains an ATP-driven ion pump in its vacuolar membrane that pumps potentially toxic heavy metal ions such as Zn2+ and Pb2+ into the vacuole. The pump protein exists in a phosphorylated and an unphosphorylated form and works in a similar way to the Na+-K+ pump of animal cells. To study its action, you incorporate the unphosphorylated form of the protein into phospholipid vesicles containing K+ in their interiors. (You ensure that all of the protein molecules are in the same orientation in the lipid bilayer.) When you add Zn2+ and ATP to the solution outside such vesicles, you find that Zn2+ is pumped into the vesicle lumen. You then expose vesicles containing the pump protein to the solutes as shown in Table 12-17A.What would you expect to happen if you treat vesicles as in lane F, but before determining the phosphorylation state of the protein you wash away the outside buffer and replace it with a buffer containing only Zn2+?

(a) Nothing will happen. (No Zn2+ will move into the vesicle; no K+ will move out of the vesicle; the phosphorylation state of the protein will not change.)
(b) No Zn2+ will move into the vesicle; no K+ will move out of the vesicle; the protein will become unphosphorylated.
(c) A small amount of Zn2+ will move into the vesicle; no K+ will move out of the vesicle; the phosphorylation state of the protein will not change.
(d) A small amount of Zn2+ will move into the vesicle; no K+ will move out of the vesicle; the protein will become unphosphorylated.

Answer: 

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 hydrolyzes ATP?

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 hydrolyzes ATP?

(a) Na+ is bound.
(b) ADP is bound.
(c) The pump is phosphorylated.
(d) The pump changes conformation.

Answer: 

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

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

(a) Na+-coupled
(b) K+-coupled
(c) ATP-driven
(d) light-driven



Answer: 

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

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

(a) active transport
(b) free diffusion
(c) facilitated diffusion
(d) passive transport

Answer: 

Transporters, in contrast to channels, work by ________________.

Transporters, in contrast to channels, work by ________________.

(a) specific binding to solutes
(b) a gating mechanism
(c) filtering solutes by charge
(d) filtering solutes by size


Answer: 

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

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

(a) Mg2+
(b) H+
(c) K+
(d) Cl-

Answer: 

Unfortunately, the grape juice is contaminated with proteases that attack some of the transport proteins in the yeast cell membrane, and the yeast cell dies. Which of the following could account for the yeast cell's demise?

A hungry yeast cell lands in a vat of grape juice and begins to feast on the sugars there, producing carbon dioxide and ethanol in the process:

C6H12O6 + 2ADP + 2Pi + H+ 2CO2 + 2CH3CH2OH + 2ATP + 2H2O

Unfortunately, the grape juice is contaminated with proteases that attack some of the transport proteins in the yeast cell membrane, and the yeast cell dies. Which of the following could account for the yeast cell's demise?

(a) toxic buildup of carbon dioxide inside the cell
(b) toxic buildup of ethanol inside the cell
(c) diffusion of ATP out of the cell
(d) inability to import sugar into the cell


Answer: 

We can test the relative permeability of a phospholipid bilayer by using a synthetic membrane that does not contain any protein components. Some uncharged, polar molecules are found to diffuse freely across these membranes, to varying degrees. Which of the following has the lowest rate of diffusion across an artificial membrane? Why?

We can test the relative permeability of a phospholipid bilayer by using a synthetic membrane that does not contain any protein components. Some uncharged, polar molecules are found to diffuse freely across these membranes, to varying degrees. Which of the following has the lowest rate of diffusion across an artificial membrane? Why?

(a) glucose
(b) water
(c) glycerol
(d) ethanol

Answer: 

Although the extracellular environment has a high sodium ion 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 principal anion?

Although the extracellular environment has a high sodium ion 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 principal anion?

(a) HCO3-
(b) Cl-
(c) PO43-
(d) OH-


Answer: 

It is possible to follow the movement of a single molecule or a small group of molecules. This requires the use of antibodies linked to small particles of gold, which appear as dark spots when tracked through video microscopy. What is this method called? What does the abbreviation stand for?

It is possible to follow the movement of a single molecule or a small group of molecules. This requires the use of antibodies linked to small particles of gold, which appear as dark spots when tracked through video microscopy. What is this method called? What does the abbreviation stand for?

(a) SDS
(b) SPT
(c) GFP
(d) FRAP

Answer: 

We can estimate the relative mobility of a population of molecules along the surface of a living cell by fluorescently labeling the molecules of interest, bleaching the label in one small area, and then measuring the speed of signal recovery as molecules migrate back into the bleached area. What is this method called? What does the abbreviation stand for?

We can estimate the relative mobility of a population of molecules along the surface of a living cell by fluorescently labeling the molecules of interest, bleaching the label in one small area, and then measuring the speed of signal recovery as molecules migrate back into the bleached area. What is this method called? What does the abbreviation stand for?

(a) SDS
(b) SPT
(c) GFP
(d) FRAP


Answer: