BIOLec Quiz 2 (Chapter 7)

A) Permeability to glucose will increase.

A phospholipid bilayer with equal amounts of saturated and unsaturated fatty acids displays a specific permeability to glucose. What effect will increasing the proportion of unsaturated fatty acids in the bilayer have on the membrane's permeability to glucose? A) Permeability to glucose will increase. B) Permeability to glucose will decrease. C) Permeability to glucose will stay the same. D) Permeability will decrease initially then increase as the bilayer fills with glucose.

D) similarity of the drug molecule to other molecules normally transported lung cells

A research team is working on the design of a new drug for the treatment of lung cancer. To be most effective, this drug must specifically enter the cytoplasm of lung cells while not entering the cells of other tissues. Which of the following characteristics would likely enhance the specificity of this drug? A) the relative hydrophobicity of the drug molecule ; B) phospholipid composition of lung cell plasma membranes ; C) specificity of the drug molecule for binding to the extracellular matrix of lung cells ; D) similarity of the drug molecule to other molecules normally transported lung cells

A) can move laterally along the plane of the membrane

According to the fluid mosaic model of cell membranes, phospholipids ________. A) can move laterally along the plane of the membrane ; B) frequently flip-flop from one side of the membrane to the other ; C) occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of the membrane ; D) have hydrophilic tails in the interior of the membrane

D) is composed of a fluid bilayer of phospholipids with embedded amphipathic proteins

According to the fluid mosaic model, a membrane ________. A) is composed of a fluid bilayer of phospholipids between two layers of hydrophilic proteins; B) is composed of a single layer of fluid phospholipids between two layers of hydrophilic proteins ; C) is composed of a mosaic of fluid polysaccharides and amphipathic proteins ; D) is composed of a fluid bilayer of phospholipids with embedded amphipathic proteins

B) cell-cell recognition

An animal cell lacking carbohydrates on the external surface of its plasma membrane would likely be impaired in which function? A) transporting ions against an electrochemical gradient; B) cell-cell recognition ; C) attaching the plasma membrane to the cytoskeleton ; D) establishing a diffusion barrier to charged molecules

C) The two sides of a cell membrane face different environments and carry out different functions.

Cell membranes have distinct inside and outside faces. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature? A) Since the cell membrane forms a border between one cell and another in tightly packed tissues such as epithelium, the membrane must be asymmetrical. B) Since cell membranes communicate signals from one organism to another, the cell membranes must be asymmetrical. C) The two sides of a cell membrane face different environments and carry out different functions. D) Proteins only function on the cytoplasmic side of the cell membrane, which results in the membrane's asymmetrical nature.

C) amphipathic, with at least one hydrophobic region

For a protein to be an integral membrane protein, it would have to be ________. A) hydrophilic ; B) hydrophobic ; C) amphipathic, with at least one hydrophobic region ; D) exposed on only one surface of the membrane

B) Certain proteins are unique to each membrane.

In what way do the membranes of a eukaryotic cell vary? A) Phospholipids are found only in certain membranes. B) Certain proteins are unique to each membrane. C) Only certain membranes of the cell are selectively permeable. D) Some membranes have hydrophobic surfaces exposed to the cytoplasm while others have hydrophilic surfaces facing the cytoplasm.

A) increasing the proportion of unsaturated phospholipids in the membrane ;

The membranes of winter wheat are able to remain fluid when it is extremely cold by ________. A) increasing the proportion of unsaturated phospholipids in the membrane ; B) decreasing the percentage of cholesterol molecules in the membrane ; C) decreasing the number of hydrophobic proteins in the membrane ; D) increasing the proportion of glycolipids in the membrane

B) small and hydrophobic ;

What kinds of molecules pass through a cell membrane most easily? A) large and hydrophobic ; B) small and hydrophobic ; C) large polar ; D) small and ionic

B) There is random movement of substances into and out of the cell.

When a cell is in equilibrium with its environment, which of the following processes occurs for substances that can diffuse through the plasma membrane? A) There is directed movement of substances into and out of the cell. B) There is random movement of substances into and out of the cell. C) There is no movement of substances into or out of the cell. D) All movement of molecules across the plasma membrane occurs by active transport.

C) C

Which component in the accompanying figure is a microfilament (actin filament) of the cytoskeleton? A) A B) B C) C D) D

A) A

Which component in the accompanying figure is a protein fiber of the extracellular matrix? A) A B) B C) C D) E

D) E

Which component in the accompanying figure is cholesterol? A) B B) C C) D D) E

D) D

Which component in the accompanying figure is hydrophilic? A) A B) B C) C D) D

B) B

Which component in the accompanying figure plays a critical role in cell-cell recognition? A) A B) B C) C D) E

D) small ions

Which of the following are least likely to diffuse through the phospholipid bilayer of a cell membrane? A) large hydrophobic molecules ; B) small hydrophobic molecules ; C) carbon dioxide ; D) small ions

B) aquaporins

Which of the following molecules dramatically increases the rate of diffusion of water across cell membranes? A) the sodium-potassium pump ; B) aquaporins ; C) gated ion channels ; D) ATP

C) passive transport

Which of the following processes includes all of the others? A) osmosis ; B) facilitated diffusion ; C) passive transport ; D) transport of an ion down its electrochemical gradient

D) It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

Which of the following statements about diffusion is true? A) It is very rapid over long distances. B) It requires an expenditure of energy by the cell. C) It is an active process in which molecules move from a region of lower concentration to a region of higher concentration. D) It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.

C) In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.

Which of the following statements correctly describes osmosis? A) Osmosis only takes place in red blood cells. B) Osmosis is an energy-demanding or "active" process. C) In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration. D) In osmosis, solutes move across a membrane from areas of lower water concentration to areas of higher water concentration.

A) It exhibits specificity for a particular type of molecule.

Which of the following statements describes a characteristic feature of a carrier protein in a plasma membrane? A) It exhibits specificity for a particular type of molecule. B) It requires the expenditure of cellular energy to function. C) It works against diffusion. D) It has no hydrophobic regions.

A) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.

Which of the following statements is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures? A) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly. B) Unsaturated fatty acids have a higher cholesterol content, which prevents adjacent lipids from packing tightly. C) Unsaturated fatty acids are more nonpolar than saturated fatty acids. D) The double bonds block interaction among the hydrophilic head groups of the lipids.

C) peripheral membrane proteins

Which of the following types of molecules are hydrophilic and therefore excluded from the hydrophobic portion of the phospholipid bilayer? A) transmembrane proteins ; B) integral membrane proteins ; C) peripheral membrane proteins ; D) cholesterol

D) cholesterol

Which of the following types of molecules lack hydrophilic domains? A) transmembrane proteins ; B) integral membrane proteins ; C) peripheral membrane proteins; D) cholesterol

C) O2

Which of the following would likely diffuse through the lipid bilayer of a plasma membrane most rapidly? A) sucrose B) an amino acid C) O2 D) Na+

D) There are only weak hydrophobic interactions in the interior of the membrane.

Why are lipids and proteins free to move laterally in membranes? A) The interior of the membrane is filled with liquid water. B) Lipids and proteins repulse each other in the membrane. C) Hydrophilic portions of the lipids are in the interior of the membrane. D) There are only weak hydrophobic interactions in the interior of the membrane.