Term
1. Biological membranes are composed of
a. nucleotides and nucleosides.
b. enzymes, electron acceptors, and electron donors.
c. fatty acids.
d. monosaccharides.
e. lipids, proteins, and carbohydrates |
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Definition
| lipids, proteins, and carbohydrates. |
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Term
2. The compounds in biological membranes that form a barrier to the movement of hydrophilic materials across the membrane are
a. integral membrane proteins.
b. carbohydrates.
c. lipids.
d. nucleic acids.
e. peripheral membrane proteins. |
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Definition
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Term
3. Which of the following is not one of the functional roles of membrane proteins?
a. Allowing movement of molecules that otherwise would be excluded by the lipid components of the membrane
b. Transferring signals from outside the cell to inside the cell
c. Facilitating the movement of water across the membrane
d. Facilitating the transport of macromolecules across the membrane
e. Stabilizing the lipid bilayer |
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Definition
| Stabilizing the lipid bilayer |
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Term
4. Which of the following statements about cholesterol molecules is true?
a. They help hold a membrane together.
b. They alter the fluidity of the membrane.
c. They attach to carbohydrates.
d. They disrupt membrane function.
e. They transport ions across membranes |
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Definition
| They alter the fluidity of the membrane. |
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Term
5. In biological membranes, the phospholipids are arranged in a _______, with the _______.
a. bilayer; fatty acids pointing toward each other
b. bilayer; fatty acids facing outward
c. single layer; fatty acids facing the interior of the cell
d. single layer; phosphorus-containing region facing the interior of the cell
e. bilayer; phosphorus groups in the interior of the membrane |
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Definition
| bilayer; fatty acids pointing toward each other |
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Term
6. Houseplants adapted to indoor temperatures may die if they are left outdoors, because in a cold environment their
a. DNA cannot function.
b. membranes lack adequate fluidity.
c. photosynthesis is impaired.
d. membranes contain too many unsaturated fatty acids.
e. membranes need more cholesterol. |
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Definition
| membranes lack adequate fluidity. |
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Term
7. Contact with ice numbs a person’s fingers because at lower temperatures
a. membrane fluidity is reduced in nerve cells.
b. no ATP can be produced in the fingers.
c. protein kinases are activated in the nerves.
d. membranes in nerve cells unzip.
e. there are changes in the lipid composition of the membranes in nerve cells. |
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Definition
| membrane fluidity is reduced in nerve cells. |
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Term
8. In hibernating animals during the winter,
a. signal transduction pathways cease.
b. membrane lipid composition changes: saturated fatty acids are replaced with unsaturated fatty acids.
c. membranes toughen as more saturated fatty acids accumulate in them.
d. there are no changes in lipid composition.
e. integral proteins shrink as temperatures fall. |
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Definition
| membrane lipid composition changes: saturated fatty acids are replaced with unsaturated fatty acids |
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Term
9. A characteristic of plasma membranes that helps them fuse during vesicle formation and phagocytosis is the
a. ratio of one protein molecule for every 25 phospholipid molecules.
b. capacity of lipids to associate and maintain a bilayer organization.
c. constant length of the fatty acid chain and the degree of saturation.
d. ability of phospholipid molecules to flip over and trade places with other phospholipid molecules.
e. asymmetrical distribution of membrane proteins. |
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Definition
| capacity of lipids to associate and maintain a bilayer organization. |
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Term
10. The plasma membranes of winter wheat are able to remain fluid when it is extremely cold by
a. increasing the number of cholesterol molecules present.
b. closing protein channels.
c. decreasing the number of hydrophobic proteins present.
d. replacing saturated fatty acids with unsaturated fatty acids.
e. using fatty acids with longer tails. |
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Definition
| replacing saturated fatty acids with unsaturated fatty acids. |
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Term
11. Which type of membrane protein would likely be most easily removed in a laboratory experiment?
a. Integral proteins
b. Channel proteins
c. Peripheral proteins
d. Transmembrane proteins
e. Gated channels |
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Definition
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Term
12. A protein that forms an ion channel through a membrane is most likely
a. a peripheral protein.
b. a transmembrane protein.
c. a phospholipid.
d. an enzyme.
e. entirely outside the phospholipid bilayer. |
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Definition
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Term
13. The LDL receptor is an integral protein that crosses the plasma membrane, with portions of the protein extending both outside and into the interior of the cell. The amino acid side chains (R groups) in the region of the protein that crosses the membrane are most likely
a. charged.
b. hydrophilic.
c. hydrophobic.
d. carbohydrates.
e. lipids. |
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Definition
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Term
14. The hydrophilic regions of a membrane protein are most likely
a. present only in muscle cells.
b. associated with the fatty acid region of the lipids.
c. in the interior of the membrane.
d. exposed on the surface of the membrane.
e. either on the surface or inserted into the interior of the membrane. |
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Definition
| d. exposed on the surface of the membrane. |
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Term
15. Which of the following statements about peripheral membrane proteins is true?
a. They have hydrophobic regions within the lipid portion of the bilayer.
b. They have hydrophilic regions that protrude in aqueous environments on both sides of the membrane.
c. They frequently flip from one side of the bilayer to the other.
d. They control the rate of diffusion.
e. Their polar regions interact with similar regions of integral membrane proteins. |
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Definition
| e. Their polar regions interact with similar regions of integral membrane proteins. |
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Term
16. The two sides of a membrane can be split apart from each other by an experimental technique known as freeze-fracturing. When one side of a freeze-fractured membrane is examined under the electron microscope, the exposed interior of the membrane bilayer appears to be covered with bumps. These bumps are most likely
a. integral membrane proteins.
b. ice crystals.
c. glycolipids.
d. organelles.
e. vesicles. |
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Definition
| a. integral membrane proteins. |
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Term
17. Which of the following functions as a recognition signal for interactions between cells?
a. RNA
b. Phospholipid
c. Cholesterol
d. Fatty acid
e. Glycolipid |
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Definition
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Term
18. When a mouse cell and a human cell are fused, the membrane proteins of the two cells become uniformly distributed over the surface of the hybrid cell. This occurs because
a. many proteins can move around within the bilayer.
b. all proteins are anchored within the membrane.
c. proteins are asymmetrically distributed within the membrane.
d. all proteins in the plasma membrane are peripheral.
e. different membranes contain different proteins. |
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Definition
| many proteins can move around within the bilayer. |
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Term
19. Which of the following is an example of passive transport?
a. Facilitated diffusion
b. The sodium–potassium pump
c. Phagocytosis
d. Exocytosis
e. Pinocytosis |
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Definition
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Term
20. Osmosis is a specific form of
a. diffusion.
b. pinocytosis.
c. active transport.
d. secondary active transport.
e. movement of water by carrier proteins. |
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Definition
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Term
21. The rate at which a substance diffuses is not affected by the
a. diameter of the molecules or ions.
b. temperature of the solution.
c. color of the substance.
d. concentration gradient in the system.
e. Both a and b |
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Definition
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Term
22. The existence of a concentration gradient of glucose across a membrane means that
a. there is a high concentration of glucose on both sides of the membrane.
b. the glucose molecules are more crowded on one side of the membrane than on the other.
c. there is a high concentration of water on both sides of the membrane.
d. the glucose molecules are chemically more tightly bonded on one side than on the other.
e. there are more glucose molecules within the membrane than outside of the membrane |
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Definition
| the glucose molecules are more crowded on one side of the membrane than on the other. |
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Term
23. If a shallow pan is filled with water, a drop of red ink is placed in one end of the pan, and a drop of green ink is placed in the other end, which of the following will be true at equilibrium?
a. The red ink will be uniformly distributed in one half of the pan, and the green ink will be uniformly distributed in the other half of the pan.
b. The red and green inks will be uniformly distributed throughout the pan.
c. Each ink will move down its concentration gradient.
d. The concentration of each ink will be higher at one end of the pan than at the other end.
e. No predictions can be made without knowing the molecular weights of the pigment molecules. |
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Definition
| The red and green inks will be uniformly distributed throughout the pan. |
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Term
24. The difference between osmosis and diffusion is that
a. diffusion is passive transport, whereas osmosis is active transport.
b. only in diffusion do molecules move from areas of high concentration to areas of low concentration.
c. only diffusion refers to the movement of materials across a semipermeable membrane.
d. osmosis refers specifically to the movement of water, whereas diffusion refers to the movement of any type of molecules.
e. the process of osmosis varies according to the kinds of particles present. |
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Definition
| osmosis refers specifically to the movement of water, whereas diffusion refers to the movement of any type of molecules. |
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Term
25. Osmosis moves water from a region of _______ to a region of _______.
a. high concentration of dissolved material; low concentration of dissolved material
b. low concentration of dissolved material; high concentration of dissolved material
c. hypertonic solution; hypotonic solution
d. hypertonic solution; isotonic solution
e. low concentration of water; high concentration of water |
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Definition
| low concentration of dissolved material; high concentration of dissolved material |
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Term
26. Which of the following statements about diffusion is false?
a. Diffusion does not require ATP.
b. Diffusion continues until the molecular concentrations are in equilibrium.
c. In diffusion, molecules move from areas of greater concentration to areas of lesser concentration.
d. Diffusion is a random process.
e. Simple diffusion depends upon specific carrier proteins. |
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Definition
| Simple diffusion depends upon specific carrier proteins. |
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Term
27. When placed in water, wilted plants lose their limpness because of
a. active transport of salts from the water into the plant cells.
b. active transport of salts into the water from the plant cells.
c. osmosis of water into the plant cells.
d. osmosis of water from the plant cells.
e. diffusion of water from the plant cells. |
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Definition
| osmosis of water into the plant cells. |
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Term
28. When a severely dehydrated patient is brought to the hospital, an IV of normal saline is started immediately. Distilled water is not used because
a. it would cause water to leave the cells of the patient and the cells would collapse.
b. nutrients are provided by the saline.
c. it would cause the patient’s blood cells to swell and eventually burst.
d. normal saline is more economical.
e. the distilled water might be contaminated by bacteria. |
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Definition
| it would cause the patient’s blood cells to swell and eventually burst. |
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Term
29. If a red blood cell is placed in an isotonic solution, it will
a. shrivel.
b. swell and burst.
c. shrivel and then return to normal.
d. swell and then return to normal.
e. take up and release water at equal rates. |
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Definition
| take up and release water at equal rates. |
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Term
30. When placed in a hypertonic solution, animal cells
a. shrink.
b. swell.
c. burst.
d. transport water out using ATP.
e. become concentrated. |
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Definition
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Term
31. Osmosis
a. helps plant cells maintain turgor pressure.
b. moves macromolecules from one cell to another.
c. facilitates the “flipping” of proteins from one side of the membrane to the other.
d. keeps concentrations uniform in all cells.
e. causes cells to lose water when they are placed in a hyptonic solution. |
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Definition
| helps plant cells maintain turgor pressure. |
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Term
32. In a hypothetical study, cells are placed in a solution of glucose in which the concentration of glucose is gradually increased. At first, the rate at which glucose enters the cells is found to increase as the concentration of the glucose solution is increased. But when the glucose concentration of the solution is increased above 10 M, the rate no longer increases. Which of the following is the likely mechanism for glucose transport into these cells?
a. Facilitated diffusion via a carrier protein
b. Facilitated diffusion via a channel protein
c. Pinocytosis
d. Secondary active transport
e. Hydrolysis |
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Definition
| Facilitated diffusion via a carrier protein |
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Term
33. Active transport usually moves molecules
a. in the same direction as diffusion moves them.
b. in a direction opposite to the one in which diffusion moves them.
c. in a direction that tends to bring about equilibrium.
d. toward higher pH.
e. from inside to outside the cell. |
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Definition
| in a direction opposite to the one in which diffusion moves them. |
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Term
34. Plant cells transport sucrose across the vacuole membrane against its concentration gradient by a process known as
a. simple diffusion.
b. active transport.
c. passive transport.
d. facilitated diffusion.
e. cellular respiration. |
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Definition
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Term
35. Which of the following is not involved in secondary active transport?
a. The direct use of ATP
b. Coupling to another transport system
c. Use of an existing concentration gradient
d. The plasma membrane
e. The ability to concentrate the transported molecule |
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Definition
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Term
36. Which of the following is the driving force for simple diffusion?
a. Concentration gradient
b. ATP hydrolysis
c. ADP hydrolysis
d. Phosphorylation
e. GTP–GDP exchange |
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Definition
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Term
37. Which of the following is the driving force for facilitated diffusion?
a. Concentration gradient
b. ATP hydrolysis
c. ADP hydrolysis
d. Phosphorylation
e. GTP–GDP exchange |
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Definition
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Term
38. Which of the following is the driving force for active transport?
a. Concentration gradient
b. ATP hydrolysis
c. ADP hydrolysis
d. Phosphorylation
e. GTP–GDP exchange |
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Definition
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Term
39. Cancer therapy often fails because
a. carrier proteins block diffusion of the drugs into the cancer cells.
b. membrane proteins pump the drugs into the cancer cells.
c. drugs diffuse into the cancer cells via simple diffusion.
d. membrane proteins actively transport the drugs out of the cancer cells.
e. channel proteins pump the drugs into the cancer cells. |
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Definition
| membrane proteins actively transport the drugs out of the cancer cells. |
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Term
40. For each molecule of ATP consumed during active transport of sodium and potassium, there is an import of _______ ion(s) and an export of _______ ion(s).
a. two Na+; three K+
b. two Na+; one K+
c. one K+; three Na+
d. two K+; three Na+
e. three K+; two Na+ |
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Definition
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Term
41. In the intestine, Na+ and an amino acid bind to the same transport protein that moves the two substances in the same direction. This is an example of
a. passive transport.
b. simple diffusion.
c. secondary active transport.
d. facilitated diffusion.
e. None of the above |
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Definition
| secondary active transport. |
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Term
42. Amino acids enter cells against their concentration gradients by means of
a. simple diffusion.
b. facilitated diffusion.
c. primary active transport.
d. secondary active transport.
e. osmosis. |
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Definition
| secondary active transport. |
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Term
43. Phagocytosis, pinocytosis, and receptor-mediated endocytosis all involve
a. the intake of large particles.
b. invagination of the plasma membrane.
c. the export of macromolecules.
d. the presence of receptor proteins.
e. the intake of fluids by the cell. |
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Definition
| invagination of the plasma membrane |
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Term
44. Receptor-mediated endocytosis is the mechanism for transport of
a. clathrin.
b. all macromolecules.
c. ions.
d. cholesterol.
e. integral membrane proteins. |
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Definition
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Term
45. Which of the following processes does not involve the uptake of materials into the cell?
a. Exocytosis
b. Pinocytosis
c. Endocytosis
d. Receptor-mediated endocytosis
e. Phagocytosis |
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Definition
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Term
46. To respond to a signal, a cell must have a(n) _______ molecule that can detect the signal.
a. paracrine
b. receptor
c. autocrine
d. responder
e. All of the above |
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Definition
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Term
47. Many of the chemical signals reaching a cell deep inside a multicellular organism come from
a. the brain.
b. the lymphatic system.
c. other cells.
d. the nervous system.
e. None of the above |
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Definition
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Term
| 48. The next component of a signal transduction pathway, after the signal itself, is a(n) a. paracrine molecule. b. responder. c. receptor. d. hormone. e. effector molecule. |
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Definition
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Term
49. The signals that bind to receptors of the same cell that made them are known as
a. paracrine signals.
b. parasitic signals.
c. autocrine signals.
d. hormones.
e. responders. |
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Definition
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Term
50. The signals that bind to receptors on nearby cells are known as
a. paracrine signals.
b. parasitic signals.
c. autocrine signals.
d. hormones.
e. responders. |
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Definition
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Term
51. Signals that travel to distant cells through the circulatory system are known as
a. paracrine signals.
b. parasitic signals.
c. autocrine signals.
d. hormones.
e. responders |
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Definition
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Term
52. Vitamin A is a relatively small, lipid-soluble molecule that can behave as a hormone. Most likely its receptor
a. is an ion channel receptor.
b. is a protein kinase receptor.
c. involves a G protein.
d. is not connected to the plasma membrane.
e. does not exist; vitamin A does not have a receptor. |
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Definition
| is not connected to the plasma membrane. |
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Term
53. A molecule that binds to the particular three-dimensional structure of another molecule’s receptor site is known as a(n)
a. responder.
b. receptor.
c. ligand.
d. ion channel.
e. filament. |
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Definition
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Term
54. In general, all cell signaling causes
a. increased expression of genes.
b. an influx of ions.
c. protein kinase activity.
d. G protein activation.
e. a change in receptor conformation. |
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Definition
| a change in receptor conformation. |
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Term
55. Which of the following statements is true?
a. For most ligand–receptor complexes, binding is favored.
b. Ligand–receptor interactions are reversible.
c. Many drugs that alter human behavior prevent the binding of receptors’ specific ligands.
d. Both a and b
e. All of the above |
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Definition
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Term
56. In what way do ligand–receptor interactions differ from enzyme–substrate reactions?
a. The ligand signal is not usually metabolized into useful products.
b. Receptor–ligand interactions do not obey the laws of mass action.
c. Inhibitors never bind to the ligand-binding site.
d. Reversibility never occurs in ligand–receptor interactions.
e. None of the above; enzyme–substrate reactions and the ligand–receptor interactions do not differ. |
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Definition
| The ligand signal is not usually metabolized into useful products. |
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Term
57. Signal ligands can be divided into two general classes according to their receptors. Which of the following are the two kinds of receptors?
a. Plasma membrane and ion channel
b. Plasma membrane and protein kinase
c. Ion channel and cytoplasmic
d. G protein–linked and protein kinase
e. Plasma membrane and cytoplasmic |
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Definition
| Plasma membrane and cytoplasmic |
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Term
58. Which of the following molecules has a protein kinase receptor?
a. Insulin
b. Estrogen
c. Acetylcholine
d. Sodium
e. G protein |
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Definition
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Term
59. Which of the following bind(s) strongly to the acetylcholine receptor?
a. Estrogen
b. Acetylcholine
c. Sodium
d. Insulin
e. Protein kinases |
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Definition
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Term
60. Which of the following statements about the insulin receptor is false?
a. It is not an ion channel.
b. It is a protein kinase receptor.
c. It catalyzes the phosphorylation of insulin response substrates.
d. It is located entirely within the cytoplasm.
e. None of the above |
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Definition
| It is located entirely within the cytoplasm. |
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Term
61. Which of the following molecules has an ion channel receptor?
a. Insulin
b. Estrogen
c. Acetylcholine
d. Epinephrine
e. None of the above |
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Definition
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Term
62. Which of the following statements about acetylcholine is true?
a. It binds to a sodium channel receptor.
b. It acts as a neurotransmitter.
c. When bound to its receptor, it allows sodium to diffuse down its concentration gradient.
d. It binds to receptors on skeletal muscle cells.
e. All of the above |
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Definition
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Term
63. Which of the following statements is false?
a. Cells are bombarded with numerous signals, but they respond to only a few.
b. A cell’s receptors determine whether or not the cell will respond to a signal.
c. Receptor proteins are very specific.
d. Protein kinase receptors are a type of cytoplasmic receptor.
e. All of the above are true. |
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Definition
| Protein kinase receptors are a type of cytoplasmic receptor. |
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Term
64. After the GTP-bound subunit of the G protein separates from the rest of the G protein, it travels until it encounters
a. an activator.
b. a receptor.
c. an effector protein.
d. a protein kinase.
e. another G protein. |
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Definition
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Term
65. For a G protein to play its part in moving events forward in a signal pathway,
a. GDP must be released, and a GTP must occupy the nucleotide-binding site.
b. GTP must be released, and a GDP must occupy the nucleotide-binding site.
c. cGMP must occupy the otherwise empty nucleotide-binding site.
d. cGMP must leave the otherwise occupied nucleotide-binding site.
e. None of the above |
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Definition
| GDP must be released, and a GTP must occupy the nucleotide-binding site. |
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Term
66. Which of the following statements is true?
a. G proteins contain only one important binding site.
b. When a G protein binds to an activated receptor protein, ADP is exchanged for ATP.
c. G protein–linked receptors are transmembrane proteins.
d. G proteins usually float free in the cytoplasm.
e. None of the above |
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Definition
| G protein–linked receptors are transmembrane proteins. |
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Term
67. If a G protein were unable to release its bound nucleotide but could hydrolyze it, signal transduction would
a. cease.
b. be continuous.
c. be unaffected.
d. be constantly switching on and off.
e. be unpredictable. |
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Definition
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Term
68. If a G protein were able to release its bound nucleotide but not hydrolyze it, signal transduction would
a. cease.
b. be continuous.
c. be unaffected.
d. be constantly switching on and off.
e. be unpredictable. |
|
Definition
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Term
69. G proteins do not bind to
a. GTP.
b. GDP.
c. their receptor.
d. effector proteins.
e. adenylyl cyclase. |
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Definition
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Term
70. Which molecule acts as a second messenger in the cascade by which epinephrine stimulates the activation of the enzyme glycogen phosphorylase?
a. Adenosine
b. Caffeine
c. Citric acid
d. Cyclic AMP
e. Adenylyl cyclase |
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Definition
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Term
71. Which of the following would likely not be observed in a person injected with epinephrine?
a. Decreased production of cAMP in liver cells
b. Inactivation of glycogen synthase
c. Increased glucose mobilization
d. Activation of G proteins
e. All of the above would occur. |
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Definition
| Decreased production of cAMP in liver cells |
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Term
72. A benefit of the many steps involved in a protein kinase cascade is that they allow for
a. activation or inhibition of many enzymes.
b. amplification of the signal.
c. distribution of the signal throughout the inside of the cell.
d. variation in the response.
e. All of the above |
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Definition
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Term
73. Which of the following represents the correct ordering of the molecules that are activated by a single molecule of epinephrine, from highest number of molecules to lowest number of molecules?
a. cAMP, protein kinase A, phosphorylase kinase, glycogen phosphorylase
b. Glycogen phosphorylase, phosphorylase kinase, protein kinase A, cAMP
c. cAMP, phosphorylase kinase, glycogen phosphorylase, protein kinase A
d. Glycogen phosphorylase, cAMP, protein kinase A, phosphorylase kinase
e. Phosphorylase kinase, glycogen phosphorylase, cAMP, protein kinase A |
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Definition
| Glycogen phosphorylase, phosphorylase kinase, protein kinase A, cAMP |
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Term
74. How does a protein kinase cascade amplify an intercellular signal?
a. Protein kinase molecules open cell junctions, amplifying the intercellular signal.
b. The activated G protein binds and activates a second protein, amplifying the signal.
c. Nitric oxide opens cell channels, which allows protein kinase molecules to move quickly from cell to cell.
d. Second messengers create shortcuts that create multiple cascades.
e. One activated receptor kinase molecule can trigger the activation of thousands of proteins. |
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Definition
| One activated receptor kinase molecule can trigger the activation of thousands of proteins. |
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Term
75. Which of the following statements about cyclic AMP is false?
a. It is formed from ATP.
b. In some circumstances it can bind to a protein kinase in the cytoplasm.
c. The enzyme adenylyl cyclase catalyzes its formation from ATP.
d. It is a second messenger.
e. It has enzymatic activity. |
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Definition
| It has enzymatic activity |
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Term
76. Which of the following enzymes is inhibited by Viagra?
a. Phosphodiesterase
b. Protein kinase
c. Adenylyl cyclase
d. Protein phosphatase
e. ATPase |
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Definition
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Term
77. Increased synthesis of phosphodiesterase would lead to
a. decreased concentration of cyclic AMP.
b. increased concentration of cyclic AMP.
c. increased concentration of epinephrine.
d. decreased concentration of G proteins.
e. inhibition of adenylyl cyclase. |
|
Definition
| decreased concentration of cyclic AMP. |
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Term
78. Many signal transduction pathways cause
a. alterations in gene expression.
b. upregulation of genes.
c. the switching off of genes.
d. an alteration of the abundance of enzymes.
e. All of the above |
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Definition
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Term
79. The molecular structure of caffeine mimics the molecular structure of
a. paracrine.
b. aspirin.
c. adenosine.
d. autocrine.
e. None of the above |
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Definition
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Term
80. Adenosine is the normal _______ for its membrane receptor.
a. antagonist
b. enzyme
c. ligand
d. fatty acid
e. carbohydrate moiety |
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Definition
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Term
| 1. Most of the lipids composing biological membranes are called _______. |
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Definition
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Term
| 2. Biological membranes are composed of a continuous phospholipid bilayer in which proteins are embedded. This general design is known as the _______ model. |
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Definition
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Term
| 3. Membrane proteins covalently bonded to carbohydrates are called _______. |
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Definition
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Term
| 4. Integral proteins that extend all the way through the bilayer and have both ends exposed are called _______ proteins. |
|
Definition
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Term
| 5. The process of random movement of molecules toward a state of equilibrium is called _______. |
|
Definition
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Term
| 6. A solution in which the solute molecules are uniformly distributed is said to be at _______. |
|
Definition
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Term
| 7. The effectiveness of many anesthetics in reducing feeling or sensation is directly related to their _______ in membrane _______. |
|
Definition
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Term
| 8. The ability of membranes to allow some substances to pass through, but not others, is called _______. |
|
Definition
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Term
| 9. Plants and some animal cells (such as red blood and kidney cells) have membrane channels that allow water to pass through. These channels are called _______. |
|
Definition
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Term
| 10. Primary active transport involves the direct hydrolysis of _______. |
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Definition
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Term
| 11. Secondary active transport does not use _______ directly. |
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Definition
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Term
| 12. The glucose transporter is a _______ protein that allows glucose to enter the cell at a faster rate than would be possible by simple diffusion |
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Definition
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Term
| 13. The process of _______ involves coated pits, clathrin, and coated vesicles. |
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Definition
| receptor-mediated endocytosis |
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Term
| 14. The process by which the plasma membrane engulfs large particles or even whole cells is called _______. |
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Definition
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Term
| 15. Typically, a signal transduction pathway involves a signal, a _______, and a response. |
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Definition
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Term
| 16. Receptors bind to their ligands noncovalently according to chemistry’s law of _______. |
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Definition
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Term
| 17. The mammalian hormone insulin binds to a _______ receptor on the outside surface of the cell and initiates a response. |
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Definition
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Term
| 18. Phosphorylation changes the _______ of a protein and thus its _______. |
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Definition
| charge (covalence); function |
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Term
| 19. An important consequence of having steps in a signal transduction cascade is that the signal is _______ with each step. |
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Definition
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Term
| 20. Caffeine restores wakefulness because it binds to receptors for _______, thus preventing this chemical from causing drowsiness. |
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Definition
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