Chapter Eight, Mastering Biology 206

Cystic fibrosis is the result of a malfunction of a cellular ABC transporter that transports A. Cl - B. vitamin B12 C. a hydrophobic drug D. glucose E. amino acids.

A. Cl -

One way in which ions are specifically transported into the cell is via A. gated channels B. carrier (permease) proteins C. ABC transporters D. uniport transporters E. simple diffusion.

A. gated channels

Each of the following molecules move across membranes by simple diffusion except A. glucose B. oxygen C. carbon dioxide D. water E. fatty acids.

A. glucose

Each of the following is a characteristic of active transport mechanisms except A. nondirectionality for moving a solute in either direction across a membrane depending on the solute concentration gradient B. sensitivity to inhibitors such as proton pump inhibitors C. moving solutes away from equilibrium across a membrane D. coupling transport of a solute down its concentration with transport of another solute up its concentration gradient via a symport or antiport mechanism E. coupling a thermodynamically unfavorable (endergonic) process with a favorable (exergonic) process.

A. nondirectionality for moving a solute in either direction across a membrane depending on the solute concentration gradient

Each of the following is an example of facilitated diffusion except A. oxygen transport B. chloride-bicarbonate exchange C. glucose transport by GLUT1 D. ion channel transport E. aquaporin transport.

A. oxygen transport

Phosphorylation of glucose following its transport into a cell A. maintains a higher level of glucose outside the cell B. increases glucose transport into the cell by increasing its concentration gradient across the plasma membrane C. targets the glucose for transport back out of the cell D. converts glucose into a form that can more easily be exported from the cell E. decreases glucose transport into the cell by decreasing its concentration gradient across the plasma membrane.

B. increases glucose transport into the cell by increasing its concentration gradient across the plasma membrane

The Na+/K+ ATPase pump actively moves A. 1 Na+ out, 1 K+ in B. .3 Na+ in 2 K+ out C. 3 Na+ out, 2 K+ in D. 2 Na+ out, 3 K+ in E. 2 Na+ in, 3 K+ out.

C. 3 Na+ out, 2 K+ in

Which of the following is an example of indirect active transport? A. CFTR Cl - transport B. aquaporin water transport C. Na+/glucose symport D. glucose permease transport E. Na+/K+ ATPase

C. Na+/glucose symport

The energy necessary to drive the bacteriorhodopsin proton pump that creates the proton gradient needed for ATP synthesis is generated by A. a membrane potential of 100 mV across the membrane B. a Na+ electrochemical gradient across the membrane C. retinal absorption of light energy D. a H+ concentration gradient across the membrane E. ATP hydrolysis by ATP synthase.

C. retinal absorption of light energy

Water moves across the plasma membrane into or out of a cell by osmosis when A. there is an equal solute concentration on both sides of the membrane B. water diffuses through a semipermeable membrane toward a lower solute concentration C. water diffuses through a semipermeable membrane toward a higher solute concentration D. ATP hydrolysis drives aquaporin transport E. a high solute concentration opens an aquaporin channel. Submit

C. water diffuses through a semipermeable membrane toward a higher solute concentration

Because the procedure you are using to modify plants requires their cell membranes to be pulled away from the cell walls by plasmolysis, you place the cells in a(n) A. isotonic solution B. hypotonic solution C. acid solution D. hypertonic solution E. basic solution.

D. hypertonic solution

The erythrocyte anion exchange protein "ping-pong" transport mechanism does not involve A. binding of bicarbonate ion on one side of the membrane B. two conformational states of the protein C. binding of Cl - on one side of the membrane D. unidirectional transport of Cl - only out of the cell E. All are involved in the mechanism

D. unidirectional transport of Cl - only out of the cell

Active transport makes it possible for cells to A. establish an electrical potential across the membrane B. take up nutrients from the environment against concentrations gradients C. maintain nonequilibrium intracellular concentrations of ions such as Na+, K+, Ca2+, and H+ D. transport out secretory products and waste material against concentration gradients E. All of the above are correct.

E. All of the above are correct.

Different ABC transporters can transport A. polysaccharides B. sugars C. amino acids and peptides D. ions E. All of the above are correct.

E. All of the above are correct.

Which of the following types of transport occur across the erythrocyte membrane? A. aquaporin water transport B. Cl - bicarbonate ion antiport C. glucose uniport D. O2 and CO2 passive diffusion E. All of the above are correct.

E. All of the above are correct.

Which of the following is a characteristic of facilitated diffusion (passive transport) of a molecule across a membrane? A. Its rate is higher than that of simple diffusion of the molecule B. The rate of transport is saturable C. The direction of transport is determined by concentration and/or electrochemical gradients D. It is highly specific for the molecule being transported E. All of the above are true.

E. All of the above are true.

The primary difference between active transport and facilitated diffusion is that active transport is the only one of the two in which A. the S concentration gradient provides the energy necessary for S transport B. the mechanism is not saturable C. transporter proteins are required D. the direction of transport is [S]high →→ [S]low E. the direction of transport is [S]low →→ [S]high.

E. the direction of transport is [S]low →→ [S]high.

Frog oocytes are a useful experimental system for studying transporters, because frog oocytes possess all of the following characteristics except A. they are large, easily injected cells B. they are relatively inexpensive and easy to obtain C. they can be maintained in little more than pure water D. they express injected heterologous mRNAs E. they express all transporters known.

E. they express all transporters known.