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Lecture 1

BIOL 1010 Lecture 1: Biology_I_Chapter_5_Membranes

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BIOL 1010

Biology I Chapter 5 Membranes LearnSmart 1. The lipid bilayer of cell membranes acts as a barrier to the free movement of substances that are o Hydrophilic o Water soluble 2. True or False: In order to survive, grow and reproduce, a cell must continually exchange materials and information with its environment. o True 3. Unlike prokaryotic cells, eukaryotic cells have internal membranes, which surround their organelles. 4. Which structure surrounds all cells? o Plasma membrane 5. A defining feature of biological membranes is the presence of which of the following? o A lipid bilayer 6. Order the following substances according to how easily they can cross the lipid bilayer of the plasma membrane without the help of transport proteins. List the substances that cross most easily first. o Nonpolar molecules o Polar molecules o Ions 7. Match each organism with the strategy it uses to maintain osmotic balance. o Oak tree ▪ Surround the cells with a rigid wall that can withstand the pressure that builds up inside the cells dues to the inflow of water by osmosis. o Paramecium ▪ Use contractile vacuoles to actively pump water out of the cells. o Humans ▪ Surround the cells with an isotonic extracellular fluid. 8. If 2 solutions have unequal concentrations of solutes, the solution with the higher solute concentration is called hypertonic and the solution with the lower solute concentration is called hypotonic. 9. Which of the following are true of the plasma membrane? o It is fluid. o It is selectively permeable. 10. Triglycerides and phospholipids are different because only phospholipids have. o A phosphate group attached to 1 carbon atom in the backbone o A polar “head” and 2 nonpolar “tails” 11. Transport that requires a cell to expand some of its own energy, typically from ATP, is called active transport. 12. When the concentration of a substance varies from one region to another, this is called which of the following? o A concentration gradient 13. Net movement of a substance from a region where it has a higher concentration to a region where it has a lower concentration is called which of the following? o Diffusion 14. Which of the following involve passive transport? o Facilitated diffusion o Diffusion 15. The most abundant molecule in the cytoplasm is the water molecule. 16. The plasma membrane can be best described as which of the following? o Selectively permeable 17. Place the following molecules in order according to their capability to cross the lipid bilayer of the plasma membrane without the help of transport proteins. Start with molecules that cross most easily. o Nonpolar molecules o Small polar molecules o Large polar molecules 18. A solution where water is the solvent is called an aqueous solution. 19. When 10 grams of sugar are dissolved in 1 L of water, water is the solvent and sugar is the solute. 20. Which of the following are mechanisms of active transport? o Sodium potassium pump o Coupled transport 21. The diffusion of these molecules across a selectively permeable membrane is called osmosis. o Water 22. Transport that occurs without a cell expending any of its own energy is called passive transport. 23. When phospholipids are placed in water, they spontaneously from which of the following? o A bilayer 24. An aqueous solution with a higher concentration of solutes will have a lower concentration of free water molecules. 25. Which of the following describes facilitated diffusion? o It requires a concentration gradient. o It requires the assistance of proteins. 26. Which of the following involves active transport? o Movement of a substance against its own concentration gradient 27. Which of the following are required for the sodium potassium pump cells to work? o Carrier proteins o ATP 28. Order the following changes that take place during the sodium potassium pump cycle, beginning with the binding of Na to the cytoplasmic side of the carrier. o Three Na bind to the cytoplasmic side of the carrier. o The carrier is phosphorylated by ATP. o The carrier changes shape and releases 3 Na into the extracellular fluid. o Two K bind to the extracellular side of the carrier. o The carrier is dephosphorylated. o The carrier changes shapes and releases 2 K into the cytoplasm. 29. If 2 solutions have the same concentration of solutes, they are isotonic. 30. When the concentration of a substance varies from one region to another, this substance is said to exhibit a concentration gradient. 31. During transport via the sodium potassium pump which of the following occurs? o Sodium ions inside the cell bind with the carrier protein. o Dephosphorylation of the carrier protein causes it to change shape and release potassium ions inside the cell. 32. Which of the following describes passive transport? o It does not require an expenditure of energy by the cell itself. 33. Facilitated diffusion by carrier proteins differs from simple diffusion due to which of the following? o Only facilitated diffusion by carrier proteins exhibits saturation. 34. Which of the following describes the surface of a phospholipid bilayer? o It is polar or charged. o It is hydrophilic. 35. Of the following cells, which one is likely to burst when placed in a hypotonic solution? o Animal cell 36. Water is attracted to which kind of solutes, forming hydration shells around them? o Polar o Charged 37. While active transport requires the cell to expend some of its own energy, passive transport does not. 38. Suppose a dialysis bag containing a 1% starch solution is placed in a beaker containing a 0.1% starch solution. Water is the solvent and water can pass through the dialysis membrane but starch cannot. Which of the following occurs before equilibrium is reached? o Some water molecules move out of the bag. o Net movement of water is into the bag. 39. In an aqueous solution the solvent is water. 40. Suppose a hypertonic solution and hypotonic solution are separated by a selectively permeable membrane that allows water to pass through freely but prevents the passage of solutes. Before equilibrium is reached, which of the following statements are true? o The hypertonic solution has a higher concentration of solutes. 41. Why is active transport such an important cell process? o Only active transport can move a substance from an area where it has a lower concentration to an area where it has a higher concentration. 42. Among transport proteins, carrier proteins may function for either a
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