Human Physiology: An Integrated Approach, 7e, (Silverthorn)Chapter 5 Membrane Dynamics

1) Which body fluid compartment contains high levels of K+, large anions, and proteins?A) plasma onlyB) interstitial fluid only C) intracellular fluid only D) both plasma and intracellular fluidE) both plasma and interstitial fluidAnswer: CSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Knowledge

2) Which body fluid compartment contains higher levels of Na+, Cl-, and HCO3-?A) plasma onlyB) interstitial fluid onlyC) intracellular fluid onlyD) both plasma and intracellular fluidE) both plasma and interstitial fluidAnswer: ESection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Knowledge

3) All of the following are types of mediated transport EXCEPT one. Identify the exception.A) facilitated diffusionB) primary active transportC) simple diffusionD) secondary active transportAnswer: CSection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Comprehension

4) Bulk flow is fluid flow as a result of a(n) ________ gradient.A) concentrationB) electricalC) pressureD) Two of the answers are correct. E) None of the answers are correct. Answer: CSection: Transport ProcessesLearning Outcome: 5.5Bloom's Taxonomy: Comprehension

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5) Water is a polar molecule, yet it easily moves through the nonpolar portions of cell membranes. Which transport process is responsible?A) facilitated diffusionB) simple diffusionC) uniportD) symportE) antiportAnswer: BSection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Comprehension

6) Permeability is a property ofA) membranes.B) ions.C) solutes.D) solvents.E) proteins.Answer: ASection: Transport ProcessesLearning Outcome: 5.5Bloom's Taxonomy: Knowledge

7) The term cellular (metabolic) energy indicates any biological process requiringA) energy in any form.B) ATP.C) thermal energy.D) chemical energy.E) thermal energy and chemical energy.Answer: BSection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Knowledge

8) What are the two extracellular fluid compartments in the body?A) intracellular and plasmaB) plasma and interstitialC) interstitial and intracellularD) plasma and the fluid portion of the bloodE) None of the answers are correct. Answer: BSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Knowledge

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9) Saturation occurs whenA) molecules are moved by the use of vesicles.B) the energy required to move molecules results from a high-energy bond.C) a group of carrier proteins is operating at its maximum rate.D) a preference of a carrier protein for a substance is demonstrated based on the differing affinities of the carrier for the substrates.E) a carrier molecule has the ability to transport only one molecule or a group of closely related molecules.Answer: CSection: Protein-Mediated TransportLearning Outcome: 5.9Bloom's Taxonomy: Knowledge

10) The means by which a cell transports large molecules out of the cell is calledA) phagocytosis.B) endocytosis.C) exocytosis.D) diffusion.E) active transport.Answer: CSection: Vesicular TransportLearning Outcome: 5.10Bloom's Taxonomy: Knowledge

11) Which of the following is a way for solutes in an aqueous solution to move from an area of high solute concentration to an area of low solute concentration?A) only facilitated diffusionB) only osmosisC) only active transportD) both facilitated diffusion and osmosisE) None of the answers are correct. Answer: ASection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Comprehension

12) In an epithelium, the apical membrane is also known as the ________ membrane.A) basolateralB) mucosalC) serosalD) basementE) nictitatingAnswer: BSection: Epithelial TransportLearning Outcome: 5.11Bloom's Taxonomy: Knowledge

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13) Hyposmotic solutionsA) have higher concentrations of solutes than hyperosmotic solutions.B) have lower concentrations of solutes than other hyposmotic solutions.C) have the same concentration of solutes as hyperosmotic solutions.D) have lower concentrations of solutes than hyperosmotic solutions.E) None of the answers are correct. Answer: DSection: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Comprehension

14) Which of the following statements about the Na+/K+ pump is FALSE?A) It transports Na+ out of the cell and K+ into the cell.B) It is present in neurons.C) Its activity requires the expenditure of metabolic (cellular) energy.D) It transports Na+ and K+ in a 1:1 ratio.Answer: DSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

15) Which of the following statements about the resting membrane potential is TRUE?A) It is normally equal to zero volts.B) The inside of the membrane is positively charged compared to the outside.C) It results, in part, from the concentration gradients for Na+ and K+.D) It is due in part to the presence of extracellular proteins.Answer: CSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Comprehension

16) Voltage-gated (voltage-dependent) channels and antiport carriers are both types ofA) structural proteins.B) enzymes.C) transporters.D) receptors.Answer: CSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Comprehension

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17) The resting membrane potential in a typical nerve cell is approximatelyA) +70 mV.B) -70 mV.C) +35 mV.D) -35 mV.E) 0 mV.Answer: BSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Knowledge

18) Compared to the outside surface, the inside of a resting cell membrane isA) positively charged.B) negatively charged.C) electrically neutral.D) continuously reversing its electrical charge.E) positively charged whenever the sodium-potassium pump is active.Answer: BSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Knowledge

19) Caveolae and clathrin-coated pits are both used inA) endocytosis.B) exocytosis.C) phagocytosis.D) All of the answers are correct. E) None of the answers are correct.Answer: ASection: Vesicular TransportLearning Outcome: 5.10Bloom's Taxonomy: Comprehension

20) As the charge on the membrane of a typical neuron approaches 0 from -70 mV, the cell isA) only repolarizing.B) only hyperpolarizing.C) only depolarizing.D) only becoming more difficult to stimulate.E) hyperpolarizing and becoming more difficult to stimulate.Answer: CSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Comprehension

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21) The ion that plays a key role in initiating electrical signals in neurons isA) K+.B) Na+.C) Cl-.D) Ca2+.Answer: BSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Knowledge

22) Which of the following is NOT involved in creating the resting potential of a neuron?A) diffusion of potassium ions out of the cellB) diffusion of sodium ions into the cellC) resting membrane permeability for sodium ions greater than potassium ionsD) resting membrane permeability for potassium ions greater than sodium ionsAnswer: CSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Comprehension

23) Passive transport refers to a process that requires A) no energy at all.B) no cellular energy.C) no pressure gradient.D) no concentration gradient.E) no electrical gradient.Answer: BSection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Comprehension

24) Which of the following is NOT true of diffusion in the human body?A) Diffusion occurs faster at higher temperatures.B) Smaller molecules take longer to diffuse than larger ones.C) Net movement of molecules occurs until the osmolarity is equal.D) Diffusion is rapid over short distances and slower over longer distances.Answer: BSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

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25) Gated channels for sodium ions may includeA) mechanical gates, which respond to pressure.B) chemical gates, which respond to ligands.C) voltage gates, which respond to electrical signals.D) All of the answers are correct.E) None of the answers are correct. Answer: DSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Comprehension

26) When a neuron changes its ion permeability from the resting state, A) a variety of gated ion channels may open or close.B) Na+ channels may open, allowing Na+ to enter the cell.C) K+ channels must open, allowing K+ to enter the cell.D) only a variety of gated ion channels may open or close and Na+ channels may open, allowing Na+ to enter the cell.E) a variety of gated ion channels may open or close, Na+ channels may open, allowing Na+ to enter the cell, and K+ channels must open, allowing K+ to enter the cell.Answer: DSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Comprehension

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Match the membrane protein with its function.

A. transfer signals from the extracellular environment to the cytoplasm of the cell B. form cell-to-cell connections C. bind to molecules to facilitate entry to or exit from the cellD. ligands bind to these proteins and are changed by the protein

27) structural proteinsAnswer: BSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

28) enzymesAnswer: DSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

29) receptorsAnswer: ASection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

30) transportersAnswer: CSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

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Match the transport process to its description.

A. active transport B. passive transport

31) the movement of molecules from an area of high concentration to an area of low concentrationAnswer: CSection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Comprehension

32) the movement of molecules via proteins embedded in the cell membrane; requires ATPAnswer: ASection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Comprehension

33) the movement of molecules against the concentration gradientAnswer: ASection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Knowledge

34) tends to create an equilibrium stateAnswer: BSection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Comprehension

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Match the transport process to its description.

A. simple diffusionB. facilitated diffusionC. bothD. neither

35) the movement of molecules from an area of high concentration to an area of low concentrationAnswer: CSection: Diffusion, Protein-Mediated TransportLearning Outcome: 5.7, 5.8Bloom's Taxonomy: Knowledge

36) the use of ATP to move moleculesAnswer: DSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

37) a form of mediated transportAnswer: BSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

38) conform(s) to the properties of specificity, competition, and saturationAnswer: BSection: Protein-Mediated TransportLearning Outcome: 5.9Bloom's Taxonomy: Comprehension

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Match the type of transport with its description.

A. secretionB. paracellular transportC. transcellular transportD. absorption

39) between adjacent cellsAnswer: BSection: Epithelial TransportLearning Outcome: 5.11Bloom's Taxonomy: Comprehension

40) from an organ's lumen to the extracellular fluidAnswer: DSection: Epithelial TransportLearning Outcome: 5.11Bloom's Taxonomy: Comprehension

41) in one side of a cell and out the otherAnswer: CSection: Epithelial TransportLearning Outcome: 5.11Bloom's Taxonomy: Comprehension

42) movement from the extracellular fluid into the lumen of an organAnswer: ASection: Epithelial TransportLearning Outcome: 5.11Bloom's Taxonomy: Comprehension

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Match the terms to changes presented, assuming a resting membrane potential of -70 mV. Answers may be used once, more than once, or not at all.

A. electrical polarizationB. hyperpolarizationC. depolarizationD. repolarizationE. more than one of the answers

43) to -50 mV from resting potentialAnswer: CSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Knowledge

44) to -70 mV from -50 mVAnswer: DSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Knowledge

45) to -90 mV from resting potentialAnswer: BSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Knowledge

46) to +30 mV from resting potentialAnswer: CSection: The Resting Membrane PotentialLearning Outcome: 5.11Bloom's Taxonomy: Knowledge

47) to -70 mV from -90 mVAnswer: DSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Knowledge

48) any value other than 0 mV, regardless of relationship to resting potentialAnswer: ASection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Knowledge

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Match the potential or potential change with the causative circumstances. Assume ion movements are net movements. Answers may be used more than once or not at all.

A. resting membrane potentialB. hyperpolarizationC. depolarizationD. repolarizationE. more than one of the answers

49) Na+ enters the cellAnswer: CSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Comprehension

50) K+ leaves the cellAnswer: ESection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Comprehension

51) Cl- enters the cellAnswer: BSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Comprehension

52) membrane potential is 0 mVAnswer: CSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Knowledge

53) This type of membrane protein extends all the way through the cell membrane into both the extra- and intracellular fluids: ________.Answer: membrane-spanningSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

54) The membrane proteins that catalyze reactions that take place on the external or internal surface of the cell are ________.Answer: enzymesSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

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55) The membrane proteins that bind to a ligand and act in the body's chemical signaling system are ________.Answer: receptorsSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

56) The membrane proteins that provide for support of the cell membrane and allow for cells to connect to each other are ________.Answer: structural proteinsSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

57) The membrane proteins that change shape and bind with specific molecules to transport them across the cell membrane are ________.Answer: carrier proteinsSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

58) Carrier proteins operating at their maximum rate are said to be ________.Answer: saturatedSection: Protein-Mediated TransportLearning Outcome: 5.9Bloom's Taxonomy: Knowledge

59) The three types of gated channels are ________, ________, and ________.Answer: chemically gated channels, voltage-gated channels, mechanically gated channelsSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

60) Membrane protein pores that can be opened and closed are called ________ channels.Answer: gated (regulated)Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

61) The Na+-K+-ATPase pumps (this number of) ________ Na+ ions ________ (into/out of) the cell and (this number of) ________ K+ ions ________ (into/out of) the cell.Answer: 3 Na+, out of, 2 K+, intoSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Knowledge

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62) A pump that helps maintain an electrical gradient, such as the Na+-K+-ATPase is a(n) ________ pump.Answer: electrogenicSection: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Comprehension

63) Channel proteins that allow water to pass are called ________.Answer: aquaporinsSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

64) Membrane protein pores that are essentially always open are called ________ or ________ channels.Answer: open, leak (either order)Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

65) Which of the following is a unique characteristic of glucose as a solute in biological systems?A) It enters the interstitial fluid before going into the cell.B) It is freely penetrating and can pass in and out of the cells at any time.C) 100% of it is absorbed into the cell from the extracellular fluid.D) It is converted into dextrose inside the cell.Answer: CSection: Osmosis and TonicityLearning Outcome: 5.4Bloom's Taxonomy: Comprehension

66) The two extracellular compartments in the body are ________ and ________.Answer: plasma, interstitial fluidSection: Osmosis and TonicityLearning Outcome: 5.2Bloom's Taxonomy: Knowledge

67) The walls of the ________ separate the two extracellular fluid compartments.Answer: circulatory systemSection: Osmosis and TonicityLearning Outcome: 5.2Bloom's Taxonomy: Knowledge

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68) The ability of a carrier molecule to transport only one specific molecule or a group of closely related molecules is called ________.Answer: specificitySection: Protein-Mediated TransportLearning Outcome: 5.9Bloom's Taxonomy: Comprehension

69) At rest, nerve cells have an unequal distribution of ions on either side of the cell membrane, producing the ________.Answer: resting membrane potentialSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Comprehension

70) At rest, nerve cells have a voltage of ________ mV.Answer: -70 (Note to instructor: All nerve cells are different, so you may wish to accept a range of similar values instead of insisting on precisely this value.)Section: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Knowledge

71) A cell membrane that is selectively permeableA) randomly chooses which substances will pass through.B) can change which substances pass through by changing its lipid and protein content.C) is impermeable to all substances but water.D) will only allow substances in or out if their concentration in the cell is above or below a certain point.Answer: BSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

72) Fick's law of diffusion states that the rate of diffusion across a membrane isA) proportional to surface area and membrane thickness, but inversely proportional to concentration gradient.B) proportional to concentration gradient, surface area, and membrane permeability.C) proportional to membrane permeability, but inversely proportional to concentration gradient and surface area.D) proportional to membrane thickness and surface area.Answer: BSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

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73) Which of the following would increase the rate of diffusion across a cell membrane?A) a decrease in the surface area of the membraneB) a decrease in the concentration gradientC) a decrease in membrane permeabilityD) a decrease in membrane thicknessAnswer: DSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

74) Pinocytosis and potocytosis are types ofA) endocytosis.B) exocytosis.C) phagocytosis.D) endocytosis and exocytosis.E) exocytosis and phagocytosis.Answer: ASection: Vesicular TransportLearning Outcome: 5.10Bloom's Taxonomy: Comprehension

75) Sodium ions are more concentrated in the extracellular fluid than in the intracellular fluid. This is an example ofA) electrical disequilibrium.B) osmotic equilibrium.C) chemical disequilibrium.D) failed homeostasis.Answer: CSection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Comprehension

76) The inside of a resting cell is slightly negative relative to the outside. This is an example ofA) electrical disequilibrium.B) osmotic equilibrium.C) chemical disequilibrium.D) failed homeostasis.Answer: ASection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Comprehension

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77) Which property of diffusion best helps explain the necessity of the circulatory system in multicellular organisms?A) Molecules move from an area of higher concentration to an area of lower concentration.B) Diffusion can take place in an open system or across a partition that separates two systems.C) Diffusion is rapid over short distances but much slower over long distances.D) Diffusion rate is inversely related to molecule size.Answer: CSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

78) Facilitated diffusion and active transport differ in thatA) facilitated diffusion uses cell membrane proteins to move substances, whereas active transport does not.B) facilitated diffusion uses a substrate to bind to a protein carrier, whereas active transport does not.C) ATP is necessary for active transport, but not for facilitated diffusion.D) facilitated diffusion moves water across the cell membrane, whereas active transport does not.E) potential energy is required for active transport but not for facilitated diffusion.Answer: CSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

79) Water will always move from ________ areas to ________ areas, if there are no impermeable barriers.A) hyperosmotic, hyposmoticB) hyposmotic, hyperosmoticC) isosmotic, hyposmoticD) hyperosmotic, isosmoticAnswer: BSection: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Comprehension

80) Substances that readily dissolve in water and do not readily dissolve in lipids areA) hydrophobic and lipophobic.B) hydrophilic and lipophobic.C) hydrophobic and lipophilic.D) hydrophilic and lipophilic.Answer: BSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

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81) Which of the following molecules can move across the phospholipid bilayer by simple diffusion?A) lipidsB) steroidsC) waterD) lipids and waterE) All of the answers are correct.Answer: ESection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

82) A cell that is permeable to Solute X is placed into solution containing a higher concentration of X. Diffusion occurs until equilibrium is attained. At this time,A) there is no further movement of Solute X across the membrane.B) there is no further change in concentration of Solute X.C) Both of the statements are correct. D) Neither of the statements is correct.Answer: BSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Application

83) Cations will ________ each other.A) attractB) repelC) not react withAnswer: BSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

84) Anions will ________ each other.A) attractB) repelC) not react withAnswer: BSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

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85) The cell membrane acts as a goodA) electrical insulator.B) electrical conductor.C) electrical gradient.D) source of ions.Answer: ASection: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Comprehension

86) Describe the distribution of water in the body's fluid compartments.Answer: 67% is intracellular.33% is extracellular; of that 75% is in the interstitial fluid and 25% is in the plasma.Section: Osmosis and TonicityLearning Outcome: 5.2Bloom's Taxonomy: Comprehension

87) Explain why transporting epithelial cells are said to be polarized. What does it mean when a nerve cell is said to be polarized?Answer: Transport epithelia have cells that are polarized with respect to distribution of transport proteins in the apical and basolateral membranes, i.e., different types of transporters in the two membranes. Nerve cells are electrically polarized, meaning that the inside of the membrane is charged relative to the outside.Section: Epithelial TransportLearning Outcome: 5.11Bloom's Taxonomy: Comprehension

88) Explain the term resting membrane potential difference.Answer: See "The Resting Membrane Potential" section of the chapter.Section: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Comprehension

89) Evaluate the validity of this statement: "The extracellular and intracellular fluid compartments have a stable solute composition that is in equilibrium."Answer: This statement is only partially true. The two compartments have stable solute compositions, but they are not in equilibrium. We use the term dynamic disequilibrium to describe this relationship.Section: Osmosis and TonicityLearning Outcome: 5.2Bloom's Taxonomy: Comprehension

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90) Explain how the body can be in a state of osmotic equilibrium and chemical disequilibrium.Answer: Osmotic equilibrium occurs because water moves freely between most cells and the extracellular fluid. Water will continue to move across membranes into more highly concentrated compartments until the concentrations (solute/volume) are equal, hence osmotic equilibrium. Osmotic equilibrium does not take into account what particles are present in each compartment, just the total number. The key is that water moves freely, but the solutes do not. Na+ and Cl- are more highly concentrated in the ECF while K+ and many anions are more highly concentrated inside the cell. Each ion is in chemical disequilibrium because it is not evenly distributed between the two compartments. Although the compartments are chemically different (chemical disequilibrium), when all solutes in one compartment are compared to all the solutes in another compartment they have the same total concentrations of solutes (are in osmotic equilibrium).Section: Osmosis and TonicityLearning Outcome: 5.1Bloom's Taxonomy: Application

91) Explain why the composition of the phospholipid bilayer determines how readily water passes through it.Answer: The phospholipid bilayer is a fluid mosaic and, depending on the function of the cell, contains various ratios of phospholipids, cholesterol, and proteins. Water molecules slip between the spaces between the fatty acid tails. Membranes with higher levels of cholesterol are less permeable to water because cholesterol fills these spaces.Section: Transport ProcessesLearning Outcome: 5.5Bloom's Taxonomy: Application

92) How do most polar molecules move through a cell membrane? Explain why water, a polar molecule, is able to cross the nonpolar portion of a cell membrane.Answer: Most polar molecules must be assisted by a protein, because the molecule will not interact with the nonpolar phospholipid tails. Examples are facilitated diffusion and active transport. Because water is very small and electrically neutral, it is able to diffuse between the phospholipid tails.Section: Protein-Mediated TransportLearning Outcome: 5.7Bloom's Taxonomy: Application

93) Water can cross a cell membrane by a variety of means. List at least three. Do water molecules cross a membrane through the same molecules as other solutes? Explain. Are all cells equally permeable to water? Explain.Answer: Water can cross through the phospholipid molecules, through special water channels called aquaporins, and through open or leak channels (pores) that also transport ions. Water can move through pores as a solvation shell around ions or independent of ions, because the watery interstitial fluid is continuous with the watery cytosol when pores are open. Some cells are more permeable to water, especially those with less cholesterol in the membranes and those with a high density of pores.Section: Osmosis and TonicityLearning Outcome: 5.1Bloom's Taxonomy: Application

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94) Explain the differences between channel proteins and carrier proteins and why cells need both.Answer: Channel proteins allow more rapid transport, but are not as selective. Carrier proteins are slower because of the conformation change. They are also more selective and can move larger molecules than channel proteins. Carrier proteins never allow free exchange across the membrane because they never create a continuous passage between the inside and outside of the cell.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

95) Briefly explain the difference between open channels and gated channels.Answer: This is discussed in the "Protein-Mediated Transport" section of the chapter.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

96) Explain the difference between Fick's law of diffusion and the flux of a molecule.Answer: Fick's law of diffusion determines the rate of diffusion. The flux of a molecule is the rate of diffusion per unit surface area of membrane.Fick's: Rate of diffusion = concentration gradient × membrane permeability × surface areaFlux = concentration gradient × membrane permeabilitySection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Application

97) Name two ways the selectivity of a channel is determined.Answer: 1. the diameter of the central pore2. the electrical charge of the amino acids that line the channelSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

98) Compare and contrast facilitated diffusion and active transport.Answer: Both involve binding of substrate to a carrier, but facilitated is passive, moving solutes down their concentration gradients, whereas active requires ATP and can move solutes against their concentration gradients.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

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99) Distinguish between these statements, explaining what is correct or incorrect about each, and what requires clarification. Relate your answers to the energy hill concept from the previous chapter.A. Passive transport requires energy.B. Active transport requires energy.C. Vesicular transport requires energy.Answer: All forms of transport require energy, because something is being moved.A. Passive transport uses the thermal energy present in the living cell to move molecules in the energetically favorable downhill direction (with concentration gradients).B. Active transport uses the energy transferred by the ATP molecule, to move molecules in the energetically unfavorable uphill direction (against concentration gradients).C. Vesicular transport uses the energy of the ATP molecule also, to move large molecules or large quantities of molecules.Section: Transport Processes, Protein-Mediated Transport, Vesicular TransportLearning Outcome: 5.6, 5.8, 5.10Bloom's Taxonomy: Application

100) Distinguish between the following terms: cotransport; antiport; symport.Answer: Cotransport is the moving of more than one kind of molecule at one time. Antiport is cotransport of two or more solutes in opposite directions across the membrane. Symport is cotransport of two or more solutes in the same direction across the membrane.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

101) Compare and contrast primary active transport and secondary active transport, noting any special differences.Answer: Both ultimately depend on the energy of ATP, but dependence is indirect in secondary, direct in primary.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

102) Explain the process of secondary active transport and how it uses ATP.Answer: Secondary active transport uses the energy released from moving one molecule down its concentration gradient to push other molecules against their concentration gradient. ATP is used to create the chemical disequilibrium (or concentration gradient) for the first molecule.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

103) Explain the purpose of having both the reversible GLUT transporters as well as the SGLT transporters in the body.Answer: See Figure 5.16 in the chapter.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

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104) Compare and contrast penetrating solutes and non-penetrating solutes.Answer: This is discussed in the "Osmosis and Tonicity" section of the chapter.Section: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Application

105) Explain the term dynamic steady state.Answer: Dynamic indicates that materials are constantly moving from compartment to compartment, but steady state implies there is no NET movement between the compartments. Section: Osmosis and TonicityLearning Outcome: 5.1Bloom's Taxonomy: Application

106) Describe the three major roles of structural proteins.Answer: 1. connect membrane to the cytoskeleton to maintain cell shape2. create cell junctions that hold tissues together3. attach cells to the extracellular matrix by linking cytoskeleton fibers to extracellular collagen and other protein fibersSection: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

107) Draw a membrane channel protein from two different perspectives, clearly indicating the pore in each.Answer: See Figure 5.11 in the chapter.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Comprehension

108) How is a carrier protein like a ship canal?Answer: See Figure 5.12 in the chapter.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Application

109) What property of some cell membranes is associated with impermeability to water molecules?Answer: Higher concentrations of cholesterol in the cell membrane reduce membrane permeability to water.Section: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

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110) Explain the process of receptor-mediated endocytosis and exocytosis.Answer: See Figure 5.19 in the chapter.Section: Vesicular TransportLearning Outcome: 5.11Bloom's Taxonomy: Comprehension

111) Explain the five rules for diffusion and the two rules for simple diffusion across a membrane.Answer: See Table 5.6 in the chapter.Section: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Comprehension

112) Write the five rules for osmolarity and tonicity. Are the relative osmolarity and tonicity of an extracellular solution compared to intracellular fluid always the same? If they are, explain why. If they are not, give specific examples of when they are different.Answer: See Table 5.4 in the chapter.Section: Osmosis and TonicityLearning Outcome: 5.4Bloom's Taxonomy: Comprehension

113) Explain and distinguish between the following: A. chemical reaction equilibriumB. chemical equilibriumC. osmotic equilibriumAnswer: A. Chemical reaction equilibrium is achieved in reversible reactions when the rate of the forward reaction equals the rate of the reverse reaction. At this state there is no net change in the concentration of reactants and products in the system. This does not mean that concentrations are equal.B. Chemical equilibrium occurs when the concentration of a particular solute in one location equals that in another. Typically the locations compared are intracellular vs. extracellular.C. Osmotic equilibrium occurs when total solute concentration is the same, though chemical disequilibrium may exist.Section: Osmosis and TonicityLearning Outcome: 5.1Bloom's Taxonomy: Comprehension

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114) You are a server in a restaurant, always interested in going the extra mile for your customers. Patrick, a regular customer in your section, has ordered sweet iced tea and has an appointment in 10 minutes, so he must drink quickly then leave. The kitchen staff makes only unsweetened tea, but there are sugar packets on the tables. What should you do for Patrick to provide the best sweet tea, and what general principle of diffusion does this illustrate? (Hint: Will sugar dissolve quickly in an iced drink?)Answer: Make sugar syrup for Patrick by heating a small amount of water with a generous amount of sugar. The sugar diffuses through the water as it dissolves, and this will occur much quicker in warm water (diffusion rate increases with increasing temperature). Then add the syrup to his iced tea and serve. Section: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Application

115) Provide the basic physics definition of the term fluid. What is bulk flow relative to body compartments? What types of matter move by bulk flow? What is fundamentally different in the behavior of these types of matter?Answer: A fluid is a substance that flows. Bulk flow is movement of a fluid, usually within a body compartment. Liquids and gases are fluids, and they flow. Gases are compressible, but liquids are not.Section: Transport ProcessesLearning Outcome: 5.5Bloom's Taxonomy: Comprehension

116) When you eat a large meal and your body absorbs a lot of glucose and that makes its way to the interstitial fluid before going into the cell. 100% of the glucose should be absorbed into the cell from the interstitial fluid. Why does nearly all of the glucose enter the cell, rather than only half of it?A) It is moved by active transport.B) It is modified by the cell, so there is still more glucose on the outside of the cell than inside it.C) Insulin forces glucose into the cell against a concentration gradient.D) The cells make ATP so fast, they use up all the glucose as soon as it enters the cell.Answer: BSection: Integrated Membrane Processes: Insulin SecretionLearning Outcome: 5.14Bloom's Taxonomy: Application

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117) If a 10% sucrose solution is separated from a 20% sucrose solution by a membrane impermeable to sucrose, in which direction will net movement of water occur?A) from the 10% sucrose solution to the 20% sucrose solution onlyB) from the 20% sucrose solution to the 10% sucrose solution only C) from the 10% sucrose solution to the 20% sucrose solution and from the 20% sucrose solution to the 10% sucrose solutionD) There will be no net movement of water in this case.E) None of the answers are correct.Answer: ASection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Application

118) If a 10% sucrose solution is separated from a 20% sucrose solution by a membrane permeable to sucrose, in which direction will net diffusion of sucrose take place?A) from the 10% sucrose solution to the 20% sucrose solutionB) from the 20% sucrose solution to the 10% sucrose solutionC) from the 10% sucrose solution to the 20% sucrose solution and from the 20% sucrose solutionD) neither from the 10% sucrose solution to the 20% sucrose solution nor from the 20% sucrose solution to the 10% sucrose solutionE) There will be no diffusion in this case.Answer: BSection: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Application

119) The concentration of calcium inside a cell is 0.3%. The concentration of calcium outside the cell is 0.1%. How could the cell transport even more calcium to the inside?A) passive transportB) active transportC) osmosisD) exocytosisE) All of the answers are correct. Answer: BSection: Transport ProcessesLearning Outcome: 5.6Bloom's Taxonomy: Application

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120) When the ions move across the cell membrane, an electrical potential change results. As you are probably aware, nerves trigger muscle movement. When you place your finger on a sharp object (such as a tack), you quickly draw your hand away and develop a sensation of pain. Which types of channels are operating under these conditions to allow nerve conduction and subsequent muscle movement?Answer: Mechanically gated (in sensory cell receptor potentials), voltage-gated (in nerve and muscle action potentials), and chemically gated (in neuromuscular synaptic transmission).Section: The Resting Membrane PotentialLearning Outcome: 5.12Bloom's Taxonomy: Application

121) Design an experiment to test whether molecular weight does indeed influence the rate of diffusion. Be sure to list all controlled variables.Answer: Answers will vary. Controlled variables may include temperature, pH, composition and volume of solvent or medium, amount of solute added. Solutes could be soluble dyes of different molecular weight, and rate of diffusion could be estimated by observing the extent of coloration around a dye crystal at specified intervals.Section: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Evaluation

122) Cells of the intestine are very permeable to water while some cells of the kidney tubule are not at all permeable to water. Can you suggest some ways these two types of cells might be structurally different from each other?Answer: Kidney cells may have fewer open channels through which water can pass, and/or they may have more cholesterol in their membranes.Section: DiffusionLearning Outcome: 5.7Bloom's Taxonomy: Analysis

123) How are molarity and osmolarity different? What property of salts necessitates this distinction? How does this property affect the behavior of water?Answer: Molarity is the number of molecules per liter of solution, while osmolarity is the number of independent particles per liter. The ionization of salt in water illustrates the importance of this distinction: one mole of sodium chloride dissociates to produce a total of two moles of particles (one mole Na+ and one mole Cl-), or two osmoles. Osmosis is diffusion of water. A one molar solution of sodium chloride (two osmolar) produces higher osmotic pressure than a one molar solution of glucose, which does not dissociate.Section: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Analysis

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124) Define osmolarity and tonicity. How are they similar? How are they different?Answer: Osmolarity refers to the concentration of individual particles in solution. Tonicity refers to the behavior of a cell in a solution. They are similar in that both are related to particles in solution. They are different in that osmolarity depends only on the total concentration of particles in solution, whereas tonicity depends on nature of the particles (i.e., are they penetrating or nonpenetrating) as well as on the concentration of the different particles. Section: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Analysis

125) Explain the steps that occur in a pancreatic beta cell so that insulin is secreted.Answer: See Figure 5.26b in the chapter.Section: Integrated Membrane Processes: Insulin SecretionLearning Outcome: 5.14Bloom's Taxonomy: Application

126) Indicate the relative osmolarities of the following solutions.Solution a: 2 osmolar NaClSolution b: 1 molar NaClSolution c: 900 milliosmolar glucose

A. a is ________ osmotic to b. D. a is ________ osmotic to c.B. b is ________ osmotic to a. E. b is ________ osmotic to c.C. c is ________ osmotic to a. F. c is ________ osmotic to b.Answer: This is easier to answer if all three solutions are described in equivalent terms. Solution b is 2 osmolar, because of the dissociation of sodium and chloride. Solution c is 0.9 osmolar.A. iso D. hyperB. iso E. hyperC. hypo F. hypoSection: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Application

127) When the kidney goes into failure, one of the signs that doctors will see is that red blood cells will crenate (shrivel up). Why does this happen in kidney failure? What process is occurring to the blood cells?Answer: Because the kidney is failing to filter particles out of the blood effectively, the plasma becomes hypertonic or hyperosmotic in comparison to the intracellular compartment of the blood cell. Since the cell membrane is impermeable to the ions, but permeable to water, water will leave the cell to try to balance the tonicity and osmolarity with the plasma and in the process the cell will shrink. Section: Osmosis and TonicityLearning Outcome: 5.4Bloom's Taxonomy: Analysis

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128) Red blood cells with an internal osmolarity of 300 mOsM are placed in the following solutions. Designate each solution according to its osmolarity and tonicity, and explain what happens to the cells and why.A. 200 mOsM NaClB. 400 mOsM ureaC. 100 mOsM urea plus 200 mOsM NaClD. 300 mOsM ureaE. 300 mOsM NaClF. 200 mOsM urea plus 300 mOsM NaClG. 400 mOsM NaClAnswer: A. Hyposmotic, hypotonic. The cell swells. By Rule 5 in Table 5.8 in the chapter, hyposmotic solutions are always hypotonic, because the intracellular solutes are mainly nonpenetrating (Rule 1) thus there will be a net flow of water into the cell. B. Hyperosmotic, hypotonic. The cell swells. Urea is a penetrating solute, so some urea will move into the cell down its concentration gradient. This will increase the osmolarity inside the cell, causing a net flow of water into the cell. C. Isosmotic, hypotonic. The cell swells. Urea is a penetrating solute, so there will be a net movement of urea into the cell, raising the osmolarity and causing a net flow of water into the cell. D. Isosmotic, hypotonic. The cell swells. Urea will penetrate the cell, raising the osmolarity and causing a net flow of water into the cell. E. Isosmotic, isotonic. No change in cell size. Sodium and chloride are nonpenetrating solutes, so there will be no net ion flow across the membrane. Because there is no osmotic pressure, there will also be no net flow of water. F. Hyperosmotic, isotonic. No change in cell size at equilibrium. Initially water leaves the cell due to the higher osmolarity outside the cell. Then, because there is a concentration gradient for urea, urea will enter the cell, increasing its osmolarity, and bringing some water into the cell. The nonpenetrating solute concentrations in cell and solution initially are equal, therefore there will be no net movement of water at equilibrium.G. Hyperosmotic, hypertonic. The cell shrinks. There are no penetrating solutes, and water exits due to the higher osmolarity.Section: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Analysis

129) There are two solutions separated by a semipermeable membrane. Solution a is 0.3 M glucose, and solution b is 0.15 M NaCl. Will there be a net flow of water across this membrane? Why or why not?Answer: In osmoles, solution a is 0.3 OsM and solution b is 0.3 OsM (because sodium and chloride dissociate into separate particles). The solutions are isosmotic, and there is no net water flow.Section: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Analysis

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130) There are two solutions separated by a semipermeable membrane. Solution a is 0.2 M NaCl and solution b is 0.1 M CaCl2. Will there be a net flow of water across the membrane? Why or why not?Answer: In osmoles, solution a is 0.4 OsM and solution b is 0.3 OsM. Solution a is hyperosmotic, so there will be a net flow of water into solution a until equilibrium is established.Section: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Analysis

131) Define the term transport maximum and describe a way cells can increase their transport capacity.Answer: The transport maximum occurs when all carrier binding sites are filled with substrate. At this point adding more substrate will no longer increase the rate of transport. In order to increase the capacity and raise the maximum rate of transport, some cells can increase the number of carrier proteins in the membrane.Section: Protein-Mediated TransportLearning Outcome: 5.9Bloom's Taxonomy: Application

132) Diuretics cause the kidneys to produce large amounts of urine. Unfortunately, they can also cause the loss of large quantities of K+ in the urine. What effect might prolonged use of diuretics have on nerve or muscle cells?Answer: Low concentrations of potassium in the blood is a condition called hypokalemia. Interstitial fluids would similarly become low in K+. As the resting potential of nerve and muscle cells depends primarily on extracellular K+ concentration, the potential would be altered. Decreased extracellular K+ would increase the concentration gradient for movement of K+ out of the cells, which would gradually hyperpolarize the potential as positive ions exit and make the cells less excitable (farther from threshold).Section: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Analysis

133) If someone has a muscle cramp or spasm, a commonly discussed treatment is to consume a banana (or another food high in potassium). Why would this be a possible treatment for muscle cramps or spasms?Answer: Potassium is a cation that leaves the cell during an action potential or depolarization of a muscle or nerve cell, and the muscle or nerve cell needs to move potassium back into the cell to allow the cell to repolarize and relax. If there is a deficiency in potassium, muscle and nerve cells may take longer to repolarize and therefore relax, so increasing your dietary intake of potassium may help cells repolarize quicker.Section: The Resting Membrane PotentialLearning Outcome: 5.13Bloom's Taxonomy: Analysis

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134) Which membrane transport process(es) is/are abnormal in people with cystic fibrosis? What is the consequence of the abnormal transport? Which organ systems are affected? How is this disease treated? How long do cystic fibrosis patients normally live? What are some of the possible causes of death related to this disease? What is the cause of cystic fibrosis?Answer: Active transport of chloride is impaired, in the airways, sweat glands, and pancreas. The affected epithelia are involved in production of sweat and mucus. Thus, the respiratory, integumentary, and digestive systems are affected. Treatments include replacement of pancreatic digestive enzymes, which are blocked from secretion by the mucus buildup in secretory ducts, and respiratory therapies to loosen mucus in the airways and treat recurring infections. Gene therapy is being explored as well. Median survival is 37 years as of the publication date of the textbook. Causes of death can be related to malnutrition and respiratory illness. This is a genetic disease, in which the gene coding for the chloride transporter is abnormal.Section: Epithelial TransportLearning Outcome: 5.11Bloom's Taxonomy: Analysis

You are walking to school one day when you notice an alien spaceship that has crashed in a nearby field. You and some other physiology students collect samples from the beings inside of the spaceship. First, you collect a liquid sample of what appears to be alien blood so that you can test for the concentration of solutes inside the alien blood cells. You then extract some of these cells, place them in various concentrations of glucose in water, then look at them under the microscope. Below is what happens to the cells when they are placed in various concentrations of glucose:

Percent Glucosein Water

Condition ofAlien Blood Cells

0.02% cells lyse0.05% cells lyse0.10% cells lyse0.12% cells crenate (shrivel up)0.20% cells crenate

Table 5.1

135) Refer to Table 5.1. From cells located in another part of the alien's body, you find that the protein-to-lipid ratio of the cell membrane is about 20% protein, 78% lipid, and 2% carbohydrate. Assuming the aliens use their cells as Earthlings do, and have the same terrestrial physiology, what is the most likely function of these cells?Answer: Similar to the myelin membrane around nerve cells—good insulators.Section: Protein-Mediated TransportLearning Outcome: 5.8Bloom's Taxonomy: Analysis

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136) Refer to Table 5.1. How can you determine the osmolarity and tonicity of the alien blood and alien cells?Answer: Quantitative chemical analysis would determine osmolarity. To determine tonicity, drop the cells into various solutions and observe the cells' response under the microscope.Section: Osmosis and TonicityLearning Outcome: 5.4Bloom's Taxonomy: Analysis

137) How does the beta cell in the pancreas react to release insulin when glucose levels are low?Answer: ATP dependent potassium gates keep the insulin releasing channels closed when there is enough glucose getting into the cell. When glucose levels drop and the amount of ATP the beta cell is making drops, it eventually loses the energy to keep the gates closed, therefore opening and allowing insulin to be released into the blood.Section: Integrated Membrane Processes: Insulin SecretionLearning Outcome: 5.14Bloom's Taxonomy: Analysis

138) What is the approximate concentration of solute present in alien blood cells?Answer: Equivalent osmolality to a 0.11% solution of glucoseSection: Osmosis and TonicityLearning Outcome: 5.4Bloom's Taxonomy: Analysis

139) A patient is given an intravenous infusion of glucose solution that has a concentration of 25 grams of glucose per liter. If the infusion is given at a rate of 4 milliliters per minute, what is the mass flow of glucose into the body?Answer: 25 g glucose/1000 mL solution × 4 mL solution/min = 0.1 g glucose/minSection: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Analysis

140) A 70-year-old man weighs 145 pounds and has 48% of his body weight in the form of water. How many liters of water is that?

Answer: 0.48 × × × 1 L = 31.64 LSection: Osmosis and TonicityLearning Outcome: 5.3Bloom's Taxonomy: Analysis

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141) A dehydrated patient needs a saline solution IV in order to be rehydrated. Unfortunately the hospital is poorly stocked with saline solutions. The nurse was asked by the doctor to mix up 1 L of a 0.45% saline solution using NaCl and distilled water. How would she do this? What is the osmolarity of this solution?Answer: 4.5 g NaCl into 950 mL of distilled water. Adjust the pH if necessary to 7.4, then add more distilled water, up to 1000 mL.

× × × = 0.154 osmoles/LSection: Osmosis and TonicityLearning Outcome: 5.4Bloom's Taxonomy: Evaluation

142) Based on what you know about the characteristics of membrane transport, explain the results shown on the graph. Each mixture consists of equal parts of glucose and fructose at the indicated concentration.

Answer: The cell has two separate membrane transport molecules, one specific for glucose and the other for fructose. The transporters become saturated somewhere between the concentrations of 0.5 mM and 1.0 mM, thus any higher concentration of these sugars produces no further increase in transport.Section: Protein-Mediated TransportLearning Outcome: 5.9Bloom's Taxonomy: Analysis

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143) You mix one liter of 300 mOsM NaCl with two liters 450 mOsM glucose. A. What is the osmolarity of the new solution? B. What is the final osmolarity of the NaCl in the new solution? C. What is the final osmolarity of glucose in the new solution? D. What is the tonicity of this new solution compared to a red blood cell with 300 mOsM nonpenetrating solute?Answer: A. 300 mOsM NaCl × 1 L = 300 mOsmoles NaCl.

450 mOsM glucose × 2 L = 900 mOsmoles glucose. Total solutes = 900 mOsmoles + 300 mOsmoles = 1200 mOsmoles. Total volume = 1 L + 2 L = 3 L. 1200 mOsmoles/3 L = 400 mOsM solution.

B. 300 mOsmoles/3 L = 100 mOsM NaCl.C. 900 mOsmoles/3 L = 300 mOsM glucose.D. Solution is hyperosmotic. Glucose is a penetrating solute, so glucose diffuses into the cell, raising the osmolarity, causing water to diffuse into the cell. The cell swells. Thus, the solution is hypotonic.Section: Osmosis and TonicityLearning Outcome: 5.3, 5.4Bloom's Taxonomy: Analysis

144) Nurse Cameron has been asked to mix an isotonic intravenous solution for an emergency room patient who has lost a lot of blood. The available solutes include glucose (m.w. 180), NaCl (m.w. 58.5), and urea (m.w. 60). How should she make up 10 L of IV solution with an osmolarity of 290 mOsm (isosmotic), making sure that it will also be isotonic?Answer: Nurse Cameron should make her solution contain only nonpenetrating solutes, i.e., she should use NaCl but not glucose or urea.10 L (0.290 Osmoles/L) (1 mole NaCl/2 Osmoles) (58.5 g/1 mole NaCl) = 84.8 g NaCl.She should add 84.8 g NaCl to about 9.5 L distilled water, mix until dissolved, adjust the pH if necessary to 7.4, then add more water to a final volume of 10 L.Section: Osmosis and TonicityLearning Outcome: 5.3, 5.4Bloom's Taxonomy: Analysis

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