Chap 7 Mastering Biology

For a protein to be an integral membrane protein, it would have to be _____. exposed on only one surface of the membrane amphipathic, with at least one hydrophobic region hydrophobic hydrophilic

amphipathic, with at least one hydrophobic region

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

Only certain molecules can cross a cell membrane.

True or false? Osmosis is a type of diffusion. True False

True

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

aquaporins

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

passive transport

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

The cell will become turgid.

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

CO2

Which statement is correct? The contents of a red blood cell are hypertonic to distilled water. A solution of distilled water is hypotonic. A solution of seawater is hypertonic.

The contents of a red blood cell are hypertonic to distilled water.

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

can move laterally along the plane of the membrane

The voltage across a membrane is called the _____. membrane potential chemical gradient electrochemical gradient osmotic potential

membrane potential

What kinds of molecules pass through a cell membrane most easily? small and hydrophobic ionic large and hydrophobic large polar

small and hydrophobic

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

the concentration gradient; ATP

The permeability of a biological membrane to a specific polar solute may depend on which of the following? the amount of cholesterol in the membrane the types of transport proteins in the membrane the phospholipid composition of the membrane the presence of unsaturated fatty acids in the membrane the types of polysaccharides present in the membrane

the types of transport proteins in the membrane

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

a proton pump

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

A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.

Active and passive transport of solutes across a membrane typically differ in which of the following ways? Active transport is usually down the concentration gradient of the solute, whereas passive transport is always against the concentration gradient of the solute. Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy. Active transport is always faster than passive transport. Active transport uses protein carriers, whereas passive transport uses carbohydrate carriers. Active transport is used for ions, passive transport is used for uncharged solutes.

Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy.

What property of dishwashing liquid (detergent) makes it useful to wash grease from pans? Permeability Solubility in water Hydrophobic nature Amphipathic nature

Amphipathic nature

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

Certain proteins are unique to each membrane.

If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell? Isotonic Hypertonic Hypotonic Osmotic

Hypotonic

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

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

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

It exhibits a specificity for a particular type of molecule.

How can a lipid be distinguished from a sugar? Lipids are mostly nonpolar. A lipid is made up of only hydrocarbons. A lipid dissolves in water. Lipids are mostly saturated.

Lipids are mostly nonpolar.

Select the correct statement about osmosis. Osmotic equilibrium cannot be reached unless solute concentrations equalize across the membrane. If a dead cell is placed in a solution hypotonic to the cell contents, osmosis will not occur. Osmosis is the diffusion of water molecules across a selectively permeable membrane.

Osmosis is the diffusion of water molecules across a selectively permeable membrane.

Which of the following particles could diffuse easily through a cell membrane? Glucose Hydrogen ion (H+) Oxygen (O2) Sodium ion (Na+)

Oxygen (O2)

You have a planar bilayer with equal amounts of saturated and unsaturated phospholipids. After testing the permeability of this membrane to glucose, you increase the proportion of unsaturated phospholipids in the bilayer. What will happen to the membrane's permeability to glucose? Permeability to glucose will stay the same. Permeability to glucose will increase. Permeability to glucose will decrease. You cannot predict the outcome. You simply have to make the measurement.

Permeability to glucose will increase.

Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean? The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism. Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life. Cells of each domain evolved proton pumps independently when oceans became more acidic. Proton pumps are necessary to all cell membranes.

Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.

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? The cell would shrink because the water in the beaker is hypotonic relative to the cytoplasm of the RBC. The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC. The cell will remain the same size because the solution outside the cell is isotonic. The cell would shrink because the water in the beaker is hypertonic relative to the cytoplasm of the RBC.

The cell would swell because the water in the beaker is hypotonic relative to the cytoplasm of the RBC.

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

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

Which of the following factors does not affect membrane permeability? The saturation of hydrocarbon tails in membrane phospholipids The amount of cholesterol in the membrane The polarity of membrane phospholipids Temperature

The polarity of membrane phospholipids

Which of the following statements about osmosis is correct? If a cell is placed in an isotonic solution, more water will enter the cell than leaves the cell. Osmotic movement of water into a cell would likely occur if the cell accumulates water from its environment. If a solution outside the cell is hypertonic compared to the cytoplasm, water will move into the cell by osmosis. Osmosis is the diffusion of water from a region of lower water concentration to a region of higher water concentration. The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.

The presence of aquaporins (proteins that form water channels in the membrane) should speed up the process of osmosis.

Which factors affect the rate of osmotic movement of water? The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane. Hydrostatic pressure applied to a hypertonic solution separated from a hypotonic solution by a selectively permeable membrane increases osmotic movement across the membrane. No factors have an effect; the rate of osmosis is constant.

The rate of osmosis increases with increasing differences in solute concentrations between two solutions separated by a selectively permeable membrane.

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

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

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

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

In facilitated diffusion, what is the role of the transport protein? Transport proteins provide a protein site for ATP hydrolysis, which facilitates the movement of a solute across a membrane. Transport proteins organize the phospholipids to allow the solute to cross the membrane. Transport proteins provide a low-resistance channel for water molecules to cross the membrane. Transport proteins provide a hydrophilic route for the solute to cross the membrane. Transport proteins provide the energy for diffusion of the solute.

Transport proteins provide a hydrophilic route for the solute to cross the membrane.

True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group. True False

True

What happens when two solutions separated by a selectively permeable membrane reach osmotic equilibrium? Water molecules no longer move between the solutions. Water molecules continue to move from the hypotonic solution to the hypertonic solution. Water molecules move between the two solutions, but there is no net movement of water across the membrane.

Water molecules move between the two solutions, but there is no net movement of water across the membrane.

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

a salmon moving from a river into an ocean

If the concentration of phosphate in the cytosol is 2.0 mM and the concentration of phosphate in the surrounding fluid is 0.1 mM, how could the cell increase the concentration of phosphate in the cytosol? passive transport diffusion active transport osmosis facilitated diffusion

active transport

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

an isotonic solution, and the plant cell is in a hypotonic solution

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

are less fluid than the surrounding membrane

In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma membrane. How do the viral glycoproteins get to the plasma membrane? They are synthesized _____. on ribosomes on the plasma membrane by ribosomes in the rough ER, secreted from the cell, and inserted into the plasma membrane from the outside on free cytoplasmic ribosomes and then inserted into the plasma membrane by ribosomes in the rough ER and arrive at the plasma membrane in the membrane of secretory vesicles

by ribosomes in the rough ER and arrive at the plasma membrane in the membrane of secretory vesicles

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

consist of protein molecules embedded in a fluid bilayer of phospholipids

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

contributes to the membrane potential

The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by which of the following? passive diffusion of the glucose through the lipid bilayer receptor-mediated endocytosis movement of glucose into the cell through a glucose channel facilitated diffusion of the glucose using a carrier protein cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

cotransport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis

Which of the following is least likely to be important in holding the components of a biological membrane together? covalent interactions between the phospholipid and protein components of the membrane hydrophobic interactions between the phospholipid tails and the surface of integral membrane proteins buried in the membrane polar interactions among the phospholipid head groups on the same surface of the membrane hydrophobic interactions among the fatty acid tails of phospholipids on the same side of the membrane hydrophobic interactions among the fatty acid tails of phospholipids on opposite sides of the membrane

covalent interactions between the phospholipid and protein components of the membrane

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

increasing the percentage of unsaturated phospholipids in the membrane

Endocytosis moves materials _____ a cell via _____. into ... membranous vesicles into ... a transport protein out of ... diffusion into ... facilitated diffusion out of ... membranous vesicles

into ... membranous vesicles

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

is a passive process in which molecules move from a region of higher concentration to a region of lower concentration

Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the fresh water_____. is hypotonic and the salt solution is hypertonic to the cells of the celery stalks is isotonic and the salt solution is hypertonic to the cells of the celery stalks is hypertonic and the salt solution is hypotonic to the cells of the celery stalks and the salt solution are both hypertonic to the cells of the celery stalks

is hypotonic and the salt solution is hypertonic to the cells of the celery stalks

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

lysosomes

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

move three sodium ions out of a cell and two potassium ions into a cell while consuming an ATP for each cycle

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

movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid

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

on the inside surface of the vesicle

What name is given to the process by which water crosses a selectively permeable membrane? pinocytosis phagocytosis diffusion passive transport osmosis

osmosis

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

peripheral proteins

A white blood cell engulfing a bacterium is an example of _____. phagocytosis pinocytosis receptor-mediated endocytosis facilitated diffusion exocytosis

phagocytosis

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

phagocytosis

Ions diffuse across membranes through specific ion channels down _____. their concentration gradients their chemical gradients their electrochemical gradients the electrical gradients

their electrochemical gradients

Which of the following best describes the structure of a biological membrane? two layers of phospholipids with proteins embedded between the two layers a mixture of covalently linked phospholipids and proteins that determines which solutes can cross the membrane and which cannot two layers of phospholipids with proteins either crossing the layers or on the surface of the layers two layers of phospholipids (with opposite orientations of the phospholipids in each layer) with each layer covered on the outside with proteins a fluid structure in which phospholipids and proteins move freely between sides of the membrane

two layers of phospholipids with proteins either crossing the layers or on the surface of the layers