Beckers World of the Cell: chapter 8a

1) 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

d

2) 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

a

(ion channel = transmembrane proteins that allow rapid passage of specific ions)

(gated channel = the pore opens and closes in response to some stimulus)

3) 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) puts glucose into a form for use in cellular respiration.

D) puts glucose into a form to be stored.

E) all of the above

e

4) 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.

b

(porin molecules are not an alpha helix but a so callad beta barrel)

(beta barrel = a water-filled pore, which allows passage of varous hydrophilic solutes, the size is limitited by the size of the pore)

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.

a

(aquaporins = facilitate the rapid movement of water molecules into or out of cell in specific tissues that require this capability)

(c: ionophores = molecules which transport ions across a cell membrane, most bacteria?)

6) 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.

d

(osmosis = movment of water through a semipermeable membrane driven by difference in solute concentration on two sides of the membrane)

7) 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

a

(hypo = lower / less)

(hyper = greater / very high)

(osmosis = from lower solute concentration to higher solute concentration)

8) 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.

e

(you want the plant cells to burst: the lower solute concentration is now inside, water tends to cross the cell wall, that is bursting in this process)

9) 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%.

e

(10 % is the highest solute concentration)

(dehydrate = all water should "leave" the cells)

10) 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.

d

(?)

11) 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

b

(?)

12) 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.

b

(?)

13) Which of the following is NOT an example of facilitated diffusion?

A) GluT1 glucose transporter

B) anion exchange protein

C) aquaporins

D) ahannel proteins

E) oxygen transport

e

(facilitated diffusion = membrane protein-mediated movement of a substance across a membrane that dies not require energy because the ion or molecule being transported is moving down an electrochemical gradient, p. 202)

(oxygen = simple diffusion)

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

A) ATP

B) oxygen

C) Na+

D) glucose

E) light

a

(ATP = needed in active transport)

15) What is the ΔG' 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

a

(???)

16) What is the ΔG' 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

d

17) What would be the net ΔG' 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

d

18) 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

19) 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

b

20) The bacteriorhodopsin proton pump creates a proton gradient necessary 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.

e

(???)

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

a

(something with the secretion of Cl- is defect)

(a defect with a membrane protein that normally serves as a channel for the movement of chloride ions across the membrane, p.208)

22) 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

b

23) Which of the following are NOT mechanisms of active transport?

A) coupled transport

B) ATP hydrolysis-driven pump

C) unidirectional movement with gradients

D) light-driven pumps

E) both C and D

c

24) The type of ATPases associated with the integral binding of ATP as part of the transport process is the

A) ABC type.

B) F type.

C) P type.

D) V type.

a

25) The Na+/K+ pump actively moves

A) 2Na+ in, 3 K+ out.

B) 2Na+ 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.

d

26) 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 choice B and C

d

("although most glucose transport occurs by facilitated diffusion... but transportproteins which uptake one gucose in exchange of two Na-ions)

27) 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 this data, substance A is transported via

A) active transport.

B) facilitated transport.

C) passive transport.

D) simple diffusion.

E) choices A, B, and C

d

28) 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) A and B only

E) all of the above

e

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

A) active transport

B) facilitated transport

C) passive transport

D) simple diffusion

E) choices A, B, and C

a

30) The primary difference between active transport and facilitated diffusion is that only in active transport

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.

c

31) 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.

a

(they do not have a cell wall)

32) Mutations in bacterial porins can lead to antibiotic resistance typically by

A) closing the a-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

c