Deck 8: Transport Across Membranes: Overcoming the Permeability Barrier

Question 1

When transporting uncharged molecules across the membrane,which of the following is/are false?

A)Keq is always equal to one.
B)ΔG is not dependent upon a gradient.
C)Movement requires a transport protein.
D)ΔG° is always equal to zero.
E)both choices A and B

Answer 1

B

Question 2

When transporting charged molecules across a membrane,which of the following is/are true?

A)When moving chloride ions in nerve cells, the movement is with both concentration and electrochemical gradients.
B)ΔG is dependent on electrochemical potential.
C)Keq is always equal to zero.
D)ΔG° is always equal to one.
E)Membrane potential is not a factor.

Answer 2

B

Question 3

Which of the following is not a characteristic of passive transport?

A)It requires binding of the molecule to be transported.
B)It is specific for the molecule being transported.
C)The energy for transport is generated by the gradient of the substance being transported.
D)The energy for transport is generated by the molecular bonds of the substance being transported.
E)Transport of the substance is the result of a conformational change.

Answer 3

D

Question 4

Facilitated diffusion implies that energy in which form is NOT required?

A)ATP
B)oxygen
C)Na⁺
D)glucose
E)light

Question 5

In the kidney,the specialized transport proteins that allow for very rapid fluid movement into or out of cells are known as

A)aquaporins.
B)porins.
C)ionophores.
D)anion exchange proteins.
E)osmosins.

Question 6

In bacteria,the porins have the unique ability to transport

A)all hydrophilic molecules.
B)hydrophilic molecules of a particular size.
C)all hydrophobic molecules.
D)hydrophobic molecules of a particular size.
E)any molecule, regardless of properties or size.

Question 7

The chloride-bicarbonate antiport is thought to function by which of the following mechanisms?

A)"ping-pong"
B)"ying-yang"
C)uniport dichotomy
D)active transport
E)induced-fit model

Question 8

Of the following molecules,which would not be expected to be moved across a membrane by simple diffusion?

A)oxygen
B)fatty acids
C)water
D)glucose
E)dimethylurea

Question 9

What is the ∆G′ for the inward transport of sucrose?

A)+1.774 kcal/mol; an endergonic reaction
B)+1.774 kcal/mol; an exergonic reaction
C)-1.774 kcal/mol; an endergonic reaction
D)-1.774 kcal/mol; an exergonic reaction
E)none of the above

Question 10

In examining glucose transport into a cell,the immediate phosphorylation of glucose following its entry into the cell

A)keeps the glucose from being transported back out of the cell.
B)allows the cell to maintain higher levels of glucose outside the cell.
C)converts glucose into a form for use in cellular respiration.
D)converts glucose into a form to be stored.
E)all of the above

Question 11

Which of the following is not an example of facilitated diffusion?

A)GLUT1 glucose transporter
B)anion exchange protein
C)aquaporins
D)channel proteins
E)oxygen transport

Question 12

Which of the following measures is used to determine a substance's polarity?

A)partition coefficient
B)extinction coefficient
C)polarity factor
D)asymmetrical distribution points
E)polarity determining factor

Question 13

Which of the following is/are true with regard to water movement in osmosis?

A)hypotonic → hypertonic
B)hypertonic → hypotonic
C)isotonic → hypotonic
D)hypertonic → isotonic
E)both choices C and D

Question 14

The movement of water through a membrane,from an area of high concentration to an area of low concentration,is known as

A)active transport.
B)facilitated transport.
C)passive transport.
D)osmosis.
E)photolysis.

Question 15

One mechanism by which ions are specifically transported into the cell is the

A)gated channel.
B)alternating conformation model.
C)carrier protein transport.
D)uniport transport model.
E)all of the above

Question 16

In all organisms,active transport across a membrane requires

A)equal concentrations of ions on both sides of the membrane.
B)a resting potential of 0 mV.
C)exergonic movement indicated by the direction of the electrochemical potential.
D)an asymmetric distribution of ions across a membrane.
E)both choices B and D

Question 17

Which of the following glucose transporters in humans has properties that facilitate glucose transport out of the cell in response to keeping blood sugar levels homeostatic?

A)GLUT1
B)GLUT2
C)GLUT3
D)GLUT4
E)GLUT5

Question 18

You wish to dehydrate a piece of meat using solutions of varying salt concentrations.The best concentration to use would be

A)0.01%.
B)0.09%.
C)0.9%.
D)1%.
E)10%.

Question 19

You are wanting to modify plant cells.With the procedure you are using,the plant cells must be in a plasmolyzed state.This means that the plant cells must be placed in a(n)

A)acid solution.
B)hypotonic solution.
C)isotonic solution.
D)basic solution.
E)hypertonic solution.

Question 20

What is the ∆G′ for the inward transport of sodium ions?

A)+5.233 kcal/mol; an endergonic reaction
B)+5.233 kcal/mol; an exergonic reaction
C)-5.233 kcal/mol; an endergonic reaction
D)-5.233 kcal/mol; an exergonic reaction
E)none of the above

Question 21

Cystic fibrosis is the result of a malfunction of the cell in transporting which of the following ions?

A)Cl⁻
B)K⁺
C)Na⁺
D)glucose
E)OH⁻

Question 22

While working with a novel cell line,you observe that movement of hydrophobic molecules,such as cholesterol and fatty acids,is impaired.You narrow the defect down to a P-type ATPase

A)type 1.
B)type 2.
C)type 3.
D)type 4.
E)type 5.

Question 23

The graph above shows the initial rate of transport for each substance when the cells are placed in solutions of different concentrations of A,B,and C.Based on these data,substance A is transported via

A)active transport.
B)facilitated transport.
C)passive transport.
D)simple diffusion.
E)choices A, B, and C

Question 24

The graph below shows the rate of transport for each substance when the cells are placed in 0.10 mM solutions of A,B,and C.Based on these data and coupled with the data observed above,substance C is transported via ________.

Question 25

Assuming no change in either the internal or external calcium ion concentration,at what membrane potential would there be no net movement of calcium across the membrane?

A)-25 mV
B)-50 mV
C)0 mV
D)+25 mV
E)+50 mV

Question 26

What would be the net ∆G′ for the coupling of these two reactions?

A)+7.007 kcal/mol
B)+3.459 kcal/mol
C)-1.774 kcal/mol
D)-3.459 kcal/mol
E)-7.007 kcal/mol

Question 27

Based on the same graph,substances B and C

A)show saturation kinetics.
B)are transported by a transporter protein.
C)do not move by simple diffusion.
D)choices A and B only
E)all of the above

Question 28

Which of the following is not a characteristic of active transport?

A)sensitive to metabolic poisons
B)exclusively move one molecule at a time in a unidirectional manner
C)can be coupled with passive transport to generate the energy necessary for active transport
D)can work as symports or antiports
E)all of the above

Question 29

Which type of ATPase is associated with the integral binding of ATP as part of the transport process?

A)ABC type
B)F type
C)P type
D)V type

Question 30

In some cells,it was noted that water moved faster than could be accounted for by simple diffusion.From this information,which of the following were identified and characterized?

A)hydroporins
B)glycoporins
C)facilitator porins
D)lipoporins
E)aquaporins

Question 31

The primary difference between active transport and facilitated diffusion is that active transport is the only one in which

A)[S]high → [S]low.
B)transporter proteins are required.
C)[S]low → [S]high.
D)the concentration gradient provides the necessary energy for movement.
E)only water molecules move.

Question 32

The bacteriorhodopsin proton pump creates a proton gradient that is needed in the process of anoxygenic photosynthesis.The energy necessary to drive this pump is generated by

A)the rhodopsin pigment directly.
B)the proton gradient itself.
C)GTP hydrolysis.
D)ATP hydrolysis.
E)light energy.

Question 33

An example of indirect active transport is

A)Na⁺/K⁺ pumps.
B)P-type ATPases.
C)ABC-type ATPases.
D)Na⁺/glucose symport.
E)both choices B and C

Question 34

Mutations in bacterial porins can lead to antibiotic resistance typically by

A)closing the α-helix of the porin.
B)limiting the passage of nonpolar substances.
C)blocking entry of the antibiotic.
D)disrupting the voltage of the gated channel.
E)all of the above

Question 35

A special class of ABC-type ATPases associated with tumors that allow movement of antibiotics and other drugs out of the cell are known as

A)multidrug resistance transport protein.
B)import transporter proteins.
C)cystic fibrosis transmembrane conductance regulator.
D)human catalytic convertase.
E)none of the above; no such transporter has been identified in eukaryotes.

Question 36

The P-type ATPases associated with the movement of heavy metals are

A)type 1.
B)type 2.
C)type 3.
D)type 4.
E)type 5.

Question 37

Which of the following is not a mechanism of active transport?

A)coupled transport
B)ATP hydrolysis-driven pump
C)unidirectional movement with gradients
D)light-driven pumps
E)both choices C and D

Question 38

Animal cells use exocytosis to secrete all of the following except

A)cell wall material.
B)mucus.
C)peptide hormones.
D)milk proteins.
E)digestive enzymes.

Question 39

What is the free energy change for the inward movement of calcium ions into the bacterial cell?

A)+4.6 kcal/mol; an endergonic reaction
B)+4.6 kcal/mol; an exergonic reaction
C)-4.6 kcal/mol; an endergonic reaction
D)-4.6 kcal/mol; an exergonic reaction
E)none of the above

Question 40

The Na⁺/K⁺ pump actively moves

A)2 Na⁺ in, 3 K⁺ out.
B)2 Na⁺ out, 3 K⁺ in.
C)3 Na⁺ in 2 K⁺ out.
D)3 Na⁺ out, 2 K⁺ in.
E)1 Na⁺ out, 1 K⁺ in.

Question 41

In the capillaries of the lungs,O₂ diffuses ________ and is bound to ________.

Question 42

In the capillaries of the body tissues,CO₂ diffuses ________ and is converted to ________.

Question 43

Pores of the outer membrane of bacteria,mitochondria,and chloroplasts that are less specific and are formed by multipass transmembrane proteins are called ________.

Question 44

The type of transport ATPase that are reversibly phosphorylated as part of the transport mechanism are the ________ ATPases.

Question 45

Brucella abortus is a bacterium that utilizes an unusual sugar,erythritol.The concentration of erythritol within the B.abortus cell is 10 mM,while the external erythritol concentration is at very low levels,such as 0.20 mM.What is the energy requirement for the inward transport of erythritol at 37°C under these conditions?

Question 46

Transmembrane movement of a substance against a concentration gradient is called ________.

Question 47

The transport of two molecules across the cell membrane in the same direction is called ________.

Question 48

The transport of two molecules across the cell membrane in different directions is called ________.

Question 49

A(n)________ solution is one that contains a solute concentration that is ________ than that within the cell and results in the "bursting" of the cell.

Question 50

Consider the glucose transporters (GLUT).In the case of GLUT1,glucose is transported into the cell for use by the cell.On the other hand,GLUT2 in liver cells allows for glucose to be released by the cells.Why would the body need GLUT systems with such variation?

Question 51

Transmembrane movement of a substance with a concentration gradient,with no involvement of membrane proteins,is called ________.

Question 52

How would known cancer cells that possess multidrug resistance transport proteins affect cancer treatment? How might you potentially counter the effect of such transporters?

Question 53

Uptake of food particles by trapping them within an invagination of the plasma membrane is called ________.

Question 54

Transmembrane movement of a substance with a concentration gradient utilizing a membrane protein is called ________.

Question 55

Receptor-mediated endocytosis involves vesicles with a special coat protein known as ________.

Question 56

What are the two most important properties that allow a molecule to cross a phospholipid bilayer by simple diffusion? What are two such molecules?

Question 57

The type of transport ATPase found in bacteria,mitochondria,and chloroplasts are the ________ ATPases.

Question 58

Design an experiment whereby you would be able to distinguish between simple diffusion and facilitated diffusion of a substance.(Include graphs,if this aids in your discussion.)