Why does a drop of food coloring diffuse more rapidly in warm water than in cold? warm water expands and provides empty space for the food coloring collisions with rapidly moving water molecules disperse the food coloring more quickly warm food coloring expands, becomes less dense, and floats toward the surface temperature differences increase the steepness of the concentration gradient all of the choices correctly describe an aspect of diffusion 1 2 3 4 5

Within the phospholipid bilayer, the hydrophobic tails of each phospholipid are ________. oriented lengthwise to form a ring around the cell oriented toward each other in opposing sheets pointed outward oriented into the nonpolar cytosol curled around the phospholipid head 1 2 3 4 5

What best explains the contribution of ATP in the active transport of calcium? ATP provides the energy needed to pump calcium with the concentration gradient ATP donates a phosphate group, which temporarily binds to the protein pump to maintain osmotic equilibrium, ATP enters the cell whenever calcium leaves ATP blocks the pump, keeping it inactive until calcium rises above normal levels since ions can't cross membranes, ATP and calcium ions react to form calcium phosphate 1 2 3 4 5

Observations of diffusion confirm that ________. larger molecules diffuse more rapidly than smaller ones diffusion can occur in liquids, but not in gels the rate of diffusion increases as the concentration gradient increases when placed in a hypertonic medium, a red blood cell will swell the energy to move molecules by diffusion comes from the hydrolysis of ATP 1 2 3 4 5

Glucose crosses the cell membrane, while galactose, a very similar molecule, cannot. How can this be explained? glucose crosses by osmosis, but no concentration gradient exists for galactose the membrane transporter is specific for glucose - galactose has a different shape and can't enter the transporter glucose is larger than galactose, so the receptor proteins bind glucose more effectively glucose is altered chemically by enzymes so that it can cross the membrane glucose gets through but galactose is blocked by osmosis 1 2 3 4 5

Which observation(s) would distinguish an active transport system from a passive system? transport rate was sensitive to temperature transport rate was sensitive to pH transport rate showed little sensitivity to concentration gradient transport rate declined when an inhibitor was used to prevent the hydrolysis of ATP all of the choices would characterize active transport 1 2 3 4 5

Which of the following do enzymes and membrane carriers have in common? they recognize molecules by shape they are made during the process of protein synthesis they are constructed from amino acids they help determine the function of the cell all of the choices are true 1 2 3 4 5

Seawater contains about 4 times as much solute as blood plasma; blood cells placed in seawater would: swell as water enters the cell by osmosis shrink as water leaves the cell by osmosis gain salt as it diffuses across the membrane lose salt as it diffuses across the membrane remain unchanged 1 2 3 4 5

Which of the following would diffuse most easily across a cell membrane? carbon dioxide glucose sodium ions proteins glycogen 1 2 3 4 5

All of the following increase the rate of diffusion across a cell membrane except ________. a steeper concentration gradient a lower temperature a smaller size an electric gradient a high osmotic pressure 1 2 3 4 5

receptor-mediated endocytosis Which process would most quickly provide a cell with relatively large amounts of a specific vitamin? active transport phagocytosis exocytosis absorption receptor-mediated endocytosis 1 2 3 4 5

bulk-phase endocytosis exocytosis receptor-mediated endocytosis The pancreatic cells producing digestive enzymes contain many Golgi bodies. It would be reasonable to assume that the membrane experiences frequent: active transport phagocytosis bulk-phase endocytosis exocytosis receptor-mediated endocytosis 1 2 3 4 5

Meals with a high salt content can temporarily cause blood plasma to become ________, and red blood cells to ________. hypotonic, shrink hypertonic, swell hypotonic, swell hypertonic, shrink hypotonic, lyse 1 2 3 4 5

there is no net movement there is no movement If a 2% sucrose solution were separated from a 7% sucrose solution by a membrane permeable to water but not sucrose, which of the following best describes the movement of water? there is no net movement there is no movement the net movement is from the 2% side to the 7% side the net movement is from the 7% side to the 2% side 1 2 3 4 5

What best explains the relationship between cystic fibrosis (CF) and the CFTR membrane protein? CFTR is an enzyme; non-degraded substrate accumulates in the cells causing CF CFTR is a receptor; cells failing to receive a growth signal die, causing CF CFTR is an adhesion protein; CF develops when lung cells detach and clog the airways CFTR is a channel protein; insufficient transport of chloride results in thickened mucus and causes CF CFTR is a recognition protein; immune-cell attack in the lungs of misidentified cells causes CF 1 2 3 4 5

diatonic isotonic hypotonic osmotonic hypertonic If a 2% sucrose solution were separated from a 7% sucrose solution by a membrane permeable to water but not sucrose, which of the following terms describes the 7% solution relative to the 2% solution? diatonic isotonic hypotonic osmotonic hypertonic 1 2 3 4 5

Polar molecules, such as the amino acids, ________. are unable to cross cell membranes and must be synthesized within the cell are enzymatically converted to nonpolar forms before crossing the membrane cross membranes by interacting with membrane transport proteins pass between the hydrophobic heads and dissolve through the hydrophilic tails of the phospholipid bilayer examples of all of the choices can be found with various molecules 1 2 3 4 5

The ________ of the plasma membrane are arranged as a ________. phospholipids, bilayer phospholipids, monolayer triglycerides, bilayer triglycerides, monolayer phospholipids, mosaic 1 2 3 4 5

facilitated diffusion passive transport hydrostatic pressure Which of the following can move substances against a concentration gradient? active transport facilitated diffusion passive transport hydrostatic pressure osmotic pressure 1 2 3 4 5

Cholesterol circulates in the blood complexed with protein because ________. without the added protein component it would be unable to cross the membrane of digestive tract cells it is a nonpolar molecule and can't dissolve in the blood plasma the molecular weight of cholesterol is too low unless other molecules are attached to it cells needing cholesterol can display the membrane receptor for the protein component all of the choices explain aspects of cholesterol transport 1 2 3 4 5