Question 1

In the microporous mem brane model, transport flux is Increased by

Accepted Answer

A)  Increasing the thickness of the mem brane 
B)  Increasing the length of each pore 
C)  Decreasing the difference in concentration across the mem brane 
D)  Increasing the size of the s olute 
E)  Increasing the number of pores per unit area of membrane 
A)  Increasing the thickness of the mem brane 
B)  Increasing the length of each pore 
C)  Decreasing the difference in concentration across the mem brane 
D)  Increasing the size of the s olute 
E)  Increasing the number of pores per unit area of membrane E

Question 2

Permeability is best defined for any mem brane as

Accepted Answer

A)  n $\pi$a2 D / ð 
B)  J /$\Delta$ C 
C)  ks D lipid /ð 
D)  D / ð 
E)  (n $\pi$a2 D + ksDlipid)/ ð 
A)  n $\pi$a2 D / ð 
B)  J /$\Delta$ C 
C)  ks D lipid /ð 
D)  D / ð 
E)  (n $\pi$a2 D + ksDlipid)/ ð B

Question 3

Permeability through the lipid bilayer

Accepted Answer

A)  Requires an input of metabolic energy 
B)  Saturates with higher concentration of solute 
C)  Always involves mo vem ent of solute from low to high osmotic pressure 
D)  Depends directly on the partition coefficient 
E)  Is increased by ionization of the solute 
A)  Requires an input of metabolic energy 
B)  Saturates with higher concentration of solute 
C)  Always involves mo vem ent of solute from low to high osmotic pressure 
D)  Depends directly on the partition coefficient 
E)  Is increased by ionization of the solute D

Question 4

Gating of ion channels means that the

Accepted Answer

A)  Specificity of ion conductance is determined by a gate 
B)  Channels appear to have gates that are opened sometimes, and closed at other times 
C)  Channels behave like sieves 
D)  Channels are like circular pipes with pressure-operated valves 
E)  Opening of the channels is metabolically controlled 
A)  Specificity of ion conductance is determined by a gate 
B)  Channels appear to have gates that are opened sometimes, and closed at other times 
C)  Channels behave like sieves 
D)  Channels are like circular pipes with pressure-operated valves 
E)  Opening of the channels is metabolically controlled

Question 5

You have the ability to measure the transport rate, Q, across a membrane as a function of the concentration of transported solute on the source side, S. How would you experimentally determine the Km for transport?

Accepted Answer

A)  It is the solute con centration at one-h alf the m ximum transport rate 
B)  It is the X -intercept on a plot of 1 /Q against 1 / S 
C)  It is the Y- interc ept o n a p lot of 1/Q against 1/ S 
D)  It is the solute concentration when Q = Q max 
E)  It is -R times the slope of the plot of ln Q vs 1/T 
A)  It is the solute con centration at one-h alf the m ximum transport rate 
B)  It is the X -intercept on a plot of 1 /Q against 1 / S 
C)  It is the Y- interc ept o n a p lot of 1/Q against 1/ S 
D)  It is the solute concentration when Q = Q max 
E)  It is -R times the slope of the plot of ln Q vs 1/T

Question 6

Facilitated diffusion differs from simple passive permeability in all of the following EXCEPT

Accepted Answer

A)  Facilitated diffusion is saturable, passive permeability is not 
B)  Facilitated diffusion uses metabolic energy, passive permeability does not 
C)  Facilitated diffusion is specific, passive permeability is not 
D)  Facilitated diffusion displays competitive inhibition, passive permeability does not 
E)  Facilitated diffusion uses a carrier, passive permeability does not 
A)  Facilitated diffusion is saturable, passive permeability is not 
B)  Facilitated diffusion uses metabolic energy, passive permeability does not 
C)  Facilitated diffusion is specific, passive permeability is not 
D)  Facilitated diffusion displays competitive inhibition, passive permeability does not 
E)  Facilitated diffusion uses a carrier, passive permeability does not

Question 7

Explain why at ste dy-state the concentration gradient in a pore must be constant.

Accepted Answer

Because if the conce ntra tion gradient

Question 8

When a solute penetrates through a membrane by dissolving in the lipid , the permeability is directly proportional to the

Accepted Answer

A)  Size of the solute 
B)  Partition coefficient 
C)  Temperature 
D)  Thickness of the membrane 
E)  Concentration difference across the membrane 
A)  Size of the solute 
B)  Partition coefficient 
C)  Temperature 
D)  Thickness of the membrane 
E)  Concentration difference across the membrane

Question 9

In the microporous model of a membrane, solutes diffuse across the membrane by

Accepted Answer

A)  Dissolving in the lipid and diffusing across the lipid phase 
B)  Diffusing through water-filled channels, or pores 
C)  Being bound to carriers that diffuse across the mem brane 
D)  Obtaining enough energy through splitting of ATP 
E)  Riding down the electrochemical gradient of Na+ 
A)  Dissolving in the lipid and diffusing across the lipid phase 
B)  Diffusing through water-filled channels, or pores 
C)  Being bound to carriers that diffuse across the mem brane 
D)  Obtaining enough energy through splitting of ATP 
E)  Riding down the electrochemical gradient of Na+

Question 10

Which of the following is NOT a characteristic of biological ion channels?

Accepted Answer

A)  They display specificity 
B)  They often display gating 
C)  They are passive 
D)  They are integral proteins 
E)  They are carriers 
A)  They display specificity 
B)  They often display gating 
C)  They are passive 
D)  They are integral proteins 
E)  They are carriers

Question 11

In carrier kinetics, saturation means that

Accepted Answer

A)  All of the carriers are busy and transport is limited by the number of carriers 
B)  No more transport is possible 
C)  Equilibrium has been reached 
D)  The membrane can hold no more solute 
E)  There are no free C=C double bonds 
A)  All of the carriers are busy and transport is limited by the number of carriers 
B)  No more transport is possible 
C)  Equilibrium has been reached 
D)  The membrane can hold no more solute 
E)  There are no free C=C double bonds

Question 12

A mem brane separates a solution with a concentration CL on the left and CR on the right. The free energy change for movem ent of solute to the right is zero when

Accepted Answer

A)  C L R 
B)  C L = RT Ln C L / CR 
C)  C R = RT Ln C L / CR 
D)  C L = CR 
E)  p = 0 
A)  C L R 
B)  C L = RT Ln C L / CR 
C)  C R = RT Ln C L / CR 
D)  C L = CR 
E)  p = 0

Question 13

In the lipid- dissolution model of passive transport, the rate- limiting step in the prrmeation is

Accepted Answer

A)  Dissolution of the solute in the lipid phase on the source side of the membrane 
B)  Dissolution of the solute in the aqueous phase on the sink side of the membrane 
C)  Diffusion of the solute through the lipid interior of the membrane 
D)  Conformational changes in the carrier 
E)  The number of pores in the membrane. 
A)  Dissolution of the solute in the lipid phase on the source side of the membrane 
B)  Dissolution of the solute in the aqueous phase on the sink side of the membrane 
C)  Diffusion of the solute through the lipid interior of the membrane 
D)  Conformational changes in the carrier 
E)  The number of pores in the membrane.

Question 14

A facilitated diffusion carrier has a Km = 5 mM and a maximum transport rate of Qmax. At a 
solute concentration of 10 mM, its transport rate is about

Accepted Answer

A)  0.25 Qmax 
B)  0.5 Qmax 
C)  0.67 Qmax 
D)  2 Qmax 
E)  Q max 
A)  0.25 Qmax 
B)  0.5 Qmax 
C)  0.67 Qmax 
D)  2 Qmax 
E)  Q max

Question 15

An ionophore is a substance that

Accepted Answer

A)  Increases the permeability of a membrane to glucose 
B)  Separates proteins on the basis of their charge and size 
C)  Carries water across membranes 
D)  Increases the permeability of a membrane to ions 
E)  Enlarges the size of water pores 
A)  Increases the permeability of a membrane to glucose 
B)  Separates proteins on the basis of their charge and size 
C)  Carries water across membranes 
D)  Increases the permeability of a membrane to ions 
E)  Enlarges the size of water pores

Question 16

Voltage- gate d channels change their open probability in response to

Accepted Answer

A)  Chemicals that bind to the channel 
B)  Current that flows through the channel 
C)  The loc al electrical field 
D)  Binding of ions to the channel 
E)  Phosphorylation of the channel 
A)  Chemicals that bind to the channel 
B)  Current that flows through the channel 
C)  The loc al electrical field 
D)  Binding of ions to the channel 
E)  Phosphorylation of the channel

Exam 10: Passive Transport and Facilitated Diffusion

In the microporous mem brane model, transport flux is Increased by

Permeability is best defined for any mem brane as

Permeability through the lipid bilayer

Gating of ion channels means that the

You have the ability to measure the transport rate, Q, across a membrane as a function of the concentration of transported solute on the source side, S. How would you experimentally determine the Km for transport?

Facilitated diffusion differs from simple passive permeability in all of the following EXCEPT

Explain why at ste dy-state the concentration gradient in a pore must be constant.

When a solute penetrates through a membrane by dissolving in the lipid , the permeability is directly proportional to the

In the microporous model of a membrane, solutes diffuse across the membrane by

Which of the following is NOT a characteristic of biological ion channels?

In carrier kinetics, saturation means that

A mem brane separates a solution with a concentration CL on the left and CR on the right. The free energy change for movem ent of solute to the right is zero when

In the lipid- dissolution model of passive transport, the rate- limiting step in the prrmeation is

A facilitated diffusion carrier has a Km = 5 mM and a maximum transport rate of Qmax. At a solute concentration of 10 mM, its transport rate is about

An ionophore is a substance that

Voltage- gate d channels change their open probability in response to

Physical Foundations Ii: Electrical Force Potential Capacitance and Current

Chemical Foundations I: Chemical Energy and Intermolecular Forces

Chemical Foundations Ii: Concentration and Kinetics

Diffusion

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Cell Structure

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Protein Structure

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Active Transport: Pumps and Exchangers

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Origin of the Membrane Potential

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Energy Balance and Regulation of Food Intake

General Principles of Endocrinology

Hypothalamus and Pituitary Gland

The Thyroid Gland

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You have the ability to measure the transport rate, Q, across a membrane as a function of the concentration of transported solute on the source side, S. How would you experimentally determine the K_m for transport?

A facilitated diffusion carrier has a K_m = 5 mM and a maximum transport rate of Q_max. At a solute concentration of 10 mM, its transport rate is about