Bio Chapter 7

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

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

The membranes of winter wheat are able to remain fluid when it is extremely cold by _____. A) increasing the percentage of unsaturated phospholipids in the membrane B) increasing the percentage of cholesterol molecules in the membrane C) decreasing the number of hydrophobic proteins in the membrane D) cotransport of glucose and hydrogen

Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. At higher temperatures, these regions _____. A) are more fluid than the surrounding membrane B) are less fluid than the surrounding membrane C) detach from the plasma membrane and clog arteries D) have higher rates of lateral diffusion of lipids and proteins into and out of these regions

Singer and Nicolson's fluid mosaic model of the membrane proposed that membranes_____. A) are a phospholipid bilayer between two layers of hydrophilic proteins B) are a single layer of phospholipids and proteins C) consist of protein molecules embedded in a fluid bilayer of phospholipids D) consist of a mosaic of polysaccharides and proteins

An animal cell lacking oligosaccharides 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

Which of these are NOT embedded in the hydrophobic portion of the lipid bilayer at all? A) transmembrane proteins B) integral proteins C) peripheral proteins D) All of these are embedded in the hydrophobic portion of the lipid bilayer.

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.

Which component is a peripheral protein? A) A B) B C) C D) D

Which component is cholesterol? A) B B) C C) D D) E

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

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

Which component is a glycolipid? A) A B) B C) C D) E

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.

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

Which of the following most accurately describes selective permeability? A) An input of energy is required for transport. B) Lipid-soluble molecules pass through a membrane. C) There must be a concentration gradient for molecules to pass through a membrane. D) Only certain molecules can cross a cell membrane.

Which of the following is a characteristic feature of a carrier protein in a plasma membrane? A) It exhibits a 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.

Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly? A) CO2 B) an amino acid C) glucose D) K+

Which of the following allows water to move much faster across cell membranes? A) the sodium-potassium pump B) ATP C) peripheral proteins D) aquaporins

Diffusion _____. A) is very rapid over long distances B) requires an expenditure of energy by the cell C) is a passive process in which molecules move from a region of higher concentration to a region of lower concentration D) requires integral proteins in the cell membrane

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

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

Which of the following is true of 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. Answer: C

Refer t o the figure. Initially, in terms of tonicity, the solution in side A with respect to the solution in side B is _____. A) hypotonic B) isotonic C) saturated D) hypertonic

Refer to the figure. After the system reaches equilibrium, what changes are observed? A) The molarity of sucrose is higher than that of glucose on side A. B) The water level is higher in side A than in side B. C) The water level is unchanged. D) The water level is higher in side B than in side A.

Refer to the figure. At the beginning of the experiment, A) side A is hypertonic to side B. B) side A is hypotonic to side B. C) side A is hypertonic to side B with respect to glucose. D) side A is hypotonic to side B with respect to NaCl.

Refer to the figure. If you examine side A after three days, you should find _____. A) a decrease in the concentration of NaCl and glucose and an increase in the water level B) a decrease in the concentration of NaCl, an increase in water level, and no change in the concentration of glucose C) a decrease in the concentration of NaCl and a decrease in the water level D) no change in the concentration of NaCl and glucose and an increase in the water level

Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment? A) A B) B C) C D) D

Which line in the graph represents the bag with the highest initial concentration of sucrose? A) A B) B C) C D) D

Which line or lines in the graph represent(s) bags that contain a solution that is hypertonic at 50 minutes? A) A and B B) B C) D D) D and E

What will happen to a red blood cell (RBC), which has an internal ion concentration of about 0.9 percent, if it is placed into a beaker of pure water? A) The cell would shrink because the water in the beaker is hypotonic relative to the cytoplasm of the RBC. B) The cell would shrink because the water in the beaker is hypertonic relative to the cytoplasm of the RBC. C) The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC. D) The cell will remain the same size because the solution outside the cell is isotonic.

Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells? The animal cell is in _____. A) a hypotonic solution, and the plant cell is in an isotonic solution B) an isotonic solution, and the plant cell is in a hypertonic solution C) a hypertonic solution, and the plant cell is in an isotonic solution D) an isotonic solution, and the plant cell is in a hypotonic solution

In which of the following would there be the greatest need for osmoregulation? A) an animal connective tissue cell bathed in isotonic body fluid B) a salmon moving from a river into an ocean C) a red blood cell surrounded by plasma D) a plant being grown hydroponically in a watery mixture of designated nutrients

When a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur? A) The cell will burst. B) Plasmolysis will shrink the interior. C) The cell will become flaccid. D) The cell will become turgid.

A sodium-potassium pump _____. A) moves three potassium ions out of a cell and two sodium ions into a cell while producing an ATP for each cycle B) move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle C) moves three potassium ions out of a cell and two sodium ions into a cell while consuming 2 ATP in each cycle D) move three sodium ions out of a cell and two potassium ions into a cell and generates an ATP in each cycle

The sodium-potassium pump is called an electrogenic pump because it _____. A) pumps equal quantities of Na+ and K+ across the membrane B) contributes to the membrane potential C) ionizes sodium and potassium atoms D) is used to drive the transport of other molecules against a concentration gradient

Which of the following membrane activities requires energy from ATP? A) facilitated diffusion of chloride ions across the membrane through a chloride channel B) movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid C) movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose than inside the cell D) movement of carbon dioxide out of a paramecium

The voltage across a membrane is called the _____. A) chemical gradient B) membrane potential C) osmotic potential D) electrochemical gradient

Ions diffuse across membranes through specific ion channels down _____. A) their chemical gradients B) their concentration gradients C) the electrical gradients D) their electrochemical gradients

Which of the following would increase the electrochemical gradient across a membrane? A) a sucrose-proton cotransporter B) a proton pump C) a potassium channel D) both a proton pump and a potassium channel

Which of the following is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal? A) Sodium and glucose compete for the same binding site in the cotransporter. B) Glucose entering the cell down its concentration gradient provides energy for uptake of sodium ions against the electrochemical gradient. C) Sodium ions can move down their electrochemical gradient through the cotransporter whether or not glucose is present outside the cell. D) A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.

The force driving simple diffusion is _____, while the energy source for active transport is _____. A) the concentration gradient; ADP B) the concentration gradient; ATP C) transmembrane pumps; electron transport D) phosphorylated protein carriers; ATP

An organism with a cell wall would most likely be unable to take in materials through _____. A) osmosis B) active transport C) phagocytosis D) facilitated diffusion

White blood cells engulf bacteria using _____. A) phagocytosis B) pinocytosis C) osmosis D) receptor-mediated exocytosis

Familial hypercholesterolemia is characterized by _____. A) defective LDL receptors on the cell membranes B) poor attachment of the cholesterol to the extracellular matrix of cells C) a poorly formed lipid bilayer that cannot incorporate cholesterol into cell membranes D) inhibition of the cholesterol active transport system in red blood cells

The difference between pinocytosis and receptor-mediated endocytosis is that _____. A) pinocytosis brings only water molecules into the cell, but receptor-mediated endocytosis brings in other molecules as well. B) pinocytosis increases the surface area of the plasma membrane, whereas receptor-mediated endocytosis decreases the plasma membrane surface area. C) pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity. D) pinocytosis can concentrate substances from the extracellular fluid, but receptor-mediated endocytosis cannot.

In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis? A) on the outside of vesicles B) on the inside surface of the cell membrane C) on the inside surface of the vesicle D) on the outer surface of the nucleus

A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in _____. A) lysosomes B) Golgi vesicles C) vacuoles D) secretory vesicles