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SC BIOL 425 - Chapter 04

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1Chapter 4: The Movement of Substances into and out of CellsMultiple-Choice Questions1. Principles of Water Movement; p. 76; easy; ans: eWater potential is defined as the:a. tendency of water to enter a cell.b. tendency of water to leave a cell.c. mechanical energy of water.d. kinetic energy of water.e. potential energy of water.2. Principles of Water Movement; p. 77; easy; ans: cThe long-distance transport of sap in the phloem is an example of:a. simple diffusion.b. facilitated diffusion.c. pressure-driven bulk flow.d. active transport.e. exocytosis.3. Principles of Water Movement; p. 77; easy; ans: cWhat is the water potential, expressed in units of megapascals, of pure water? a. –10 b. –5 c. 0 d. 10 e. 204. Principles of Water Movement; p. 77; difficult; ans: bIn the absence of other factors affecting water potential, water will move FROM a region of ______ TO a region of ______.a. low water concentration; high water concentrationb. low solute concentration; high solute concentrationc. low water potential; high water potentiald. low potential energy; high potential energye. low pressure; high pressure5. Principles of Water Movement; p. 77; moderate; ans: eWhich of the following could be the water potential of a sucrose solution at atmospheric pressure and at sea level?a. 100 MPab. 100 barsc. 10 barsd. 0 barse. –10 MPa6. Principles of Water Movement; pp. 77-78; moderate; ans: bSuppose a drop of dye is placed in one end of a tank of water. What happens next?a. Nothing happens because the molecules are at equilibrium.b. The dye molecules and the water molecules move down their respective concentration gradients.c. The dye molecules move from a region of high water potential to a region of low water potential.d. The dye molecules move against a concentration gradient.e. The water molecules move by osmosis.7. Principles of Water Movement; p. 78; moderate; ans: aWhich of the following statements about diffusion is FALSE?a. When the diffusing molecules become evenly distributed, their movement stops. b. Each of the diffusing molecules moves randomly and independently of the others. c. It is more rapid at higher than at lower temperatures.d. It involves the net movement of a substance. e. It is more rapid in gases than in liquids.8. Cells and Diffusion; p. 78; moderate; ans: cWhich of the following substances is LEAST likely to diffuse across the plasma membrane?a. waterb. a small, uncharged polar moleculec. an iond. carbon dioxidee. oxygen9. Cells and Diffusion; p. 78; difficult; ans: bWhich of the following statements about solute movement in cells is FALSE?a. Once a substance is inside a cell, it moves through the cell by diffusion.b. Diffusion is an effective way to move substances between distantly separated cells.c. Transport of substances within a cell may be speeded up by cytoplasmic streaming.d. Metabolic activities help maintain steep concentration gradients between the inside and outside of the cell.e. Within a cell, a substance may be produced in one place and used in another, thus maintaining an intracellular concentration gradient.10. Cells and Diffusion; p. 78; moderate; ans: c Which of the following is the best definition of osmosis? a. The net movement of glucose across a selectively permeable membrane.b. The net movement of any substance down a solute concentration gradient.c. The net movement of water across a selectively permeable membrane.d. The net movement of water from a region of high water potential to a region of low water potential.e. The net movement of water from a region of low water potential to a region of high water potential.11. Osmosis and Living Organisms; p. 80; moderate; ans: d Turgor pressure results most directly from: a. solutes moving out of a cell by osmosis.b. solutes moving into a cell by osmosis.c. water moving from one portion of the cytoplasm to another.d. water moving into a cell by osmosis.e. water moving out of a cell by osmosis.12. Osmosis and Living Organisms; p. 80; difficult; ans: eWall pressure:a. is the same as turgor pressure.b. develops within a cell and pushes outward against the wall.c. develops outside the cell wall and pushes inward against the wall.d. is an outwardly directed pressure of the wall.e. is an inwardly directed pressure of the wall.13. Osmosis and Living Organisms; p. 80; easy; ans: dIn plasmolysis: a. the vacuole become turgid.b. the entire cell becomes turgid.c. the cell wall shrivels into the center of the cytoplasm.d. the plasma membrane pulls away from the cell wall.e. the plasma membrane is pushed against the cell wall.14. Osmosis and Living Organisms; p. 80; moderate; ans: bIf a plant cell is placed in a solution with a relatively low water potential, the cell will:a. swell and perhaps burst.b. undergo plasmolysis.c. build up turgor pressure.d. build up wall pressure.e. neither gain nor lose water.15. Osmosis and Living Organisms; p. 81; easy; ans: cWilting results most directly from _______ in plant cells.a. increased metabolism b. malfunctioning contractile vacuoles c. the loss of turgor d. defective osmotic pressuree. defective membranes16. Structure of Cellular Membranes; p. 82; easy; ans: eWhen botanists speak of a “bilayer,” they are referring to a structure composed entirely of:a. carbohydrates.b. integral proteins.c. lectins.d. sterols.e. phospholipids.17. Structure of Cellular Membranes; p. 82; easy; ans: dThe most abundant sterol in the plant cell membrane is:a. lectin.b. cholesterol.c. triglyceride.d. stigmasterol.e. phospholipid18. Structure of Cellular Membranes; p. 82; easy; ans: bThe portion of a transmembrane protein embedded in the bilayer is:a. hydrophilic.b. hydrophobic.c. a glycoprotein.d. a glycolipid.e. a lectin.19. Structure of Cellular Membranes; p. 82; moderate; ans: dBy definition, all proteins attached to protruding portions of transmembrane proteins are:a. transmembrane proteins.b. integral proteins.c. globular proteins.d. peripheral proteins.e. glycoproteins.20. Structure of Cellular Membranes; p. 82; easy; ans: dWhich of the following statements concerning membrane structure is FALSE?a. Some proteins are firmly anchored in place. b. Some proteins move laterally within the membrane.c. Some lipids move laterally within the membrane.d. Transmembrane proteins lack hydrophilic sequences.e. Peripheral proteins lack hydrophobic sequences.21. Structure of Cellular Membranes; p. 82; moderate; ans: eAlthough membranes were previously described by the “fluid-mosaic”


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