Cell Signaling and Communication 74 Answer Key

Cell Signaling and Communication TEST FILE QUESTIONS Multiple Choice 1. Which of the following statements about cell signaling in voles is false? a. A signal transduction pathway can bring about changes in behavior. b. Oxytocin and vasopressin are signals that induce bonding and caring behaviors in voles. c. Oxytocin acts as a signal for premating behaviors. d. The interaction of the receptor and the signal causes the receptor to change shape. e. Although oxytocin and vasopressin are widely circulated in the bloodstream, they only bind to a few cell types. Answer: c Textbook Reference: 7.0 Love signals Page: 128 Bloom’s Category: 2. Understanding 2. Which of the following statements is true? a. Eukaryotic, but not prokaryotic, cells process information from their environment. b. Prokaryotic, but not eukaryotic, cells process information from their environment. c. The mere presence of a signal will cause a cell to respond to it. d. Light can be a signal. e. Sense organs allow cells to respond to physical signals but not chemical signals. Answer: d Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 129 Bloom’s Category: 2. Understanding 3. 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 Answer: b Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 129 Bloom’s Category: 2. Understanding 4. Which of the following statements is false? a. Plants respond to light as a signal. b. The environment experienced by a cell deep inside a large multicellular organism is very different from the external environment. c. Some plants are capable of responding to temperature fluctuations. d. Some cells can self-stimulate cell division by making their own division signals. e. None of the above Answer: e Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 129 Bloom’s Category: 2. Understanding 5. Most of the chemical signals coming to a cell deep inside a multicellular organism come from a. the external environment. b. the lymphatic system. c. other cells. d. the nervous system. e. None of the above Answer: c Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 129 Bloom’s Category: 2. Understanding 6. The first component of a signal transduction pathway is a(n) a. paracrine molecule. b. responder. c. receptor. d. hormone. e. effector molecule. Answer: c Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 129 Bloom’s Category: 2. Understanding 7. Signals reach target cells in multicellular organisms via _______ and _______. a. circulation; diffusion b. conduction; diffusion c. circulation; perspiration d. chaperon trafficking; transmembrane transport e. cytoskeletal trafficking; perfusion Answer: a Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 129 Bloom’s Category: 2. Understanding 8. Cells receive which of the following signals? a. Light b. Sound c. Odorants d. Hormones e. All of the above Answer: e Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 129–130 Bloom’s Category: 1. Remembering 9. 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. Answer: c Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 130 Bloom’s Category: 1. Remembering 10. 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. Answer: a Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 130 Bloom’s Category: 1. Remembering 11. 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. Answer: d Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 130 Bloom’s Category: 1. Remembering 12. Which of the following is most likely to involve the circulatory system? a. Paracrine signals b. Parasitic signals c. Autocrine signals d. Hormones e. Responders Answer: d Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 130 Bloom’s Category: 2. Understanding 13. The transmembrane protein EnvZ in a signal transduction pathway found in E. coli is an example of a(n) a. autocrine molecule. b. transductor. c. responder. d. hormone. e. None of the above Answer: e Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 131 Bloom’s Category: 4. Analyzing 14. In the E. coli signal transduction pathway, changes in the aqueous media cause part of the receptor to undergo a change in a. responder. b. conformation. c. hormonal activity. d. amplification. e. extracellular environment. Answer: b Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 131 Bloom’s Category: 2. Understanding 15. The conformational change in EnvZ causes it to become a(n) a. autocrine receptor. b. responder. c. ligand. d. protein kinase. e. phosphate group. Answer: d Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 131 Bloom’s Category: 2. Understanding 16. Which of the following is true about EnvZ? a. It phosphorylates itself during signal transduction. b. It has domains on both the inside and the outside of the cell. c. It acts as a responder. d. Both a and b e. All of the above Answer: d Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 131 Bloom’s Category: 4. Analyzing 17. The second component of a signal transduction pathway is known as a a. receptor. b. hormone. c. responder. d. transducer. e. None of the above Answer: c Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 132 Bloom’s Category: 2. Understanding 18. 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. Answer: e Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 132 Bloom’s Category: 2. Understanding 19. In order, from start to finish, the basic steps of a signal transduction pathway are a. signal, responder, receptor, effects. b. receptor, signal, responder, effects. c. signal, receptor, responder, effects. d. signal, receiver, responder, effects. e. None of the above Answer: c Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 132 Bloom’s Category: 4. Analyzing 20. In the E. coli signal transduction pathway, which of the following protein molecules acts as the responder? a. OmpR b. EnvZ c. SORp d. Autocrine e. None of the above Answer: a Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 132 Bloom’s Category: 2. Understanding 21. The phosphorylation and change in shape of the responder in the E. coli signaling transduction pathway is a key event in signaling for which of the following reasons? a. The signal that originally was on the outside of the cell has been transduced to a protein that exists totally within the cell’s cytoplasm. b. The signal has been amplified. c. The altered responder can bind to DNA and stimulate transcription of one or more genes. d. Both a and c e. All of the above Answer: e Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 132 Bloom’s Category: 4. Analyzing 22. In the E. coli signaling transduction pathway, which of the following is true about the OmpR protein? a. When phosphorylated, it acts as a transcription factor for OmpC. b. It exists both inside and outside the cell membrane. c. It is a receptor. d. Both a and b e. All of the above Answer: a Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 132 Bloom’s Category: 4. Analyzing 23. In the E. coli signaling transduction pathway, which of the following is true about OmpC? a. It is a transcription factor. b. It can insert itself into the outer membrane, resulting in the eventual restoration of homeostasis. c. It phosphorylates other proteins. d. It is a receptor. e. None of the above Answer: b Textbook Reference: 7.1 What Are Signals, and How Do Cells Respond to Them? Page: 132 Bloom’s Category: 4. Analyzing 24. Which of the following 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. There are only a few kinds of signal receptor proteins. e. None of the above Answer: d Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 132 Bloom’s Category: 2. Understanding 25. 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. Answer: c Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 132 Bloom’s Category: 1. Remembering 26. 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 the ligand–receptor interaction. e. The enzyme–substrate reaction and the ligand–receptor interaction do not differ. Answer: a Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 132 Bloom’s Category: 2. Understanding 27. Which of the following 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 binding of receptors’ specific ligands. d. Both a and b e. All of the above Answer: e Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 132–133 Bloom’s Category: 4. Analyzing 28. Caffeine mimics the molecular structure of a. paracrine. b. aspirin. c. adenosine. d. autocrine. e. None of the above Answer: c Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 133 Bloom’s Category: 2. Understanding 29. Signal molecules can be divided into two general classes according to their receptors. What are these two kinds of receptors? a. Plasma membrane and ion channel b. Plasma membrane and protein kinase c. Ion channel and protein kinase d. G protein-linked and protein kinase e. None of the above Answer: e Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 133 Bloom’s Category: 2. Understanding 30. The receptor of estrogen a. is an ion channel receptor. b. is a protein kinase receptor. c. exists within the plasma membrane. d. exists within the cytoplasm. e. None of the above Answer: d Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 133 Bloom’s Category: 2. Understanding 31. Vitamin A is a relatively small, lipid-soluble molecule that can behave as a hormone. 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. Answer: d Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 133 Bloom’s Category: 4. Analyzing 32. Which of the following molecules has an ion channel receptor? a. Insulin b. Estrogen c. Acetylcholine d. Lithium e. None of the above Answer: c Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 134 Bloom’s Category: 1. Remembering 33. Which of the following is true about acetylcholine? a. It binds to a sodium channel receptor. b. It acts as a neurotransmitter. c. The binding of two molecules of acetylcholine to a receptor are required to open the channel. d. It moves against the concentration gradient. e. All of the above Answer: e Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 134 Bloom’s Category: 2. Understanding 34. Which of the following strongly binds to the acetylcholine receptor? a. Estrogen b. Acetylcholine c. Sodium d. OmpC e. Protein kinases Answer: b Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 134 Bloom’s Category: 1. Remembering 35. Which of the following molecules has a protein kinase receptor? a. Insulin b. Estrogen c. Acetylcholine d. Sodium e. G proteins Answer: a Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 134 Bloom’s Category: 2. Understanding 36. Which of the following statements about the insulin receptor is false? a. It autophosphorylates. b. It requires binding by two insulin molecules to be activated. c. It catalyzes the phosphorylation of insulin response substrates. d. It is located entirely within the cytoplasm. e. None of the above Answer: d Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 134 Bloom’s Category: 2. Understanding 37. 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. Answer: c Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 134 Bloom’s Category: 2. Understanding 38. 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 Answer: a Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 134 Bloom’s Category: 2. Understanding 39. 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 receptors are single proteins that have seven distinct regions that pass through the phospholipid bilayer of the cell membrane. d. G proteins can only activate effector proteins; they cannot inhibit them. e. None of the above Answer: c Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 134–135 Bloom’s Category: 2. Understanding 40. 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. Answer: a Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 135 Bloom’s Category: 3. Applying 41. If a G protein were able to release its bound nucleotide but not to hydrolyze it, signal transduction would a. cease. b. be continuous. c. be unaffected. d. be constantly switching on and off. e. be unpredictable. Answer: b Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 135 Bloom’s Category: 3. Applying 42. Which of the following would likely not be observed in a person injected with epinephrine? a. Contraction of muscles surrounding the blood vessels that line the digestive tract b. Increased activity of heart muscle c. Increased glucose mobilization d. Activation of G proteins e. All of the above would occur. Answer: a Textbook Reference: 7.2 How Do Signal Receptors Initiate a Cellular Response? Page: 135 Bloom’s Category: 4. Analyzing 43. Which of the following is true? a. Direct transduction is more common than indirect transduction. b. In indirect transduction, second messengers mediate the interaction between the receptor and the cell’s response. c. Amplification never occurs via second messengers. d. Indirect transduction occurs at the plasma membrane. e. All of the above Answer: b Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 136 Bloom’s Category: 2. Understanding 44. What is the G protein that has been found in many human bladder cancers? a. Acetylcholine b. Rap c. Ras d. Rats e. None of the above Answer: c Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 136 Bloom’s Category: 1. Remembering 45. Which of the following is true about the abnormal form of Ras found in bladder cancer cells? a. Because it is inactive, it is unable to inhibit growth factors. b. It is always active because it is continuously bound to GTP. c. If it were inhibited, cells would continue to divide. d. It acts as an ion channel receptor. e. It stimulates epinephrine. Answer: b Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 136 Bloom’s Category: 1. Remembering 46. A benefit of the many steps involved in protein kinase cascades is that they allow for a. some specificity of the response. b. amplification of the signal. c. information to be communicated to the nucleus. d. variation in the response. e. All of the above Answer: e Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 137 Bloom’s Category: 2. Understanding 47. How does a protein kinase cascade amplify an intercellular signal? a. Protein kinase opens 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. Answer: e Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 137 Bloom’s Category: 4. Analyzing 48. During what part of the signal transduction pathway is Ras activated? a. Early in the pathway b. Around the midpoint c. Late in the pathway d. All along the pathway e. None of the above Answer: a Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 137 Bloom’s Category: 2. Understanding 49. 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 Answer: d Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 138 Bloom’s Category: 2. Understanding 50. Second messengers a. are typically very specific in their activity. b. do not amplify a signal. c. have enzymatic activity. d. can be derived from lipids. e. All of the above Answer: d Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 138 Bloom’s Category: 2. Understanding 51. Which of the following statements about cyclic AMP is false? a. It can bind to, and thus open, ion channels in some sensory cells. 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. Answer: e Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 138 Bloom’s Category: 2. Understanding 52. Which of the following statements is false? a. Diacylglycerol can act as a second messenger. b. Inositol triphosphate can act as a second messenger. c. Protein kinase C can phosphorylate a wide variety of proteins. d. Inositol triphosphate remains bound to the membrane after phospholipase C catalyzes its formation. e. Inositol triphosphate can open an ion channel, releasing calcium into the cytoplasm. Answer: d Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 138 Bloom’s Category: 2. Understanding 53. The concentration of cAMP in a cell is increased by a. phosphodiesterase. b. cGMP. c. a protein kinase. d. a second messenger. e. a G protein. Answer: e Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 138–139 Bloom’s Category: 2. Understanding 54. The hydrolysis of PIP2 results in a. inositol triphosphate and diacylglycerol. b. inositol triphosphate and cyclic AMP. c. two second messengers. d. Both a and c e. Both b and c Answer: d Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 139 Bloom’s Category: 2. Understanding 55. IP3 is released into the cytoplasm when PIP2 is hydrolyzed. IP3 a. opens Ca2+ channels. b. closes Ca2+ channels. c. stimulates G protein activation of phospholipase C. d. activates cyclic AMP. e. produces calcium-binding protein S4. Answer: a Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 139 Bloom’s Category: 2. Understanding 56. Lithium can be effective in the treatment of bipolar disorder because it a. opens up the lithium ion channel. b. acts as a second messenger accelerating the IP3/DAG signal transduction pathway. c. inhibits G protein activation of phospholipase C and inhibits synthesis of IP3. d. changes the osmotic balance of cells. e. acts as a neurotransmitter. Answer: c Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 140 Bloom’s Category: 2. Understanding 57. Which of the following statements about calcium is true? a. Calcium ions are more concentrated inside than outside the cell. b. Active transport maintains the concentration difference of calcium ions. c. A cell can increase intracellular concentrations of calcium by making more calcium. d. IP3 is the only signal that causes calcium channels to open. e. It inhibits cell division in fertilized eggs. Answer: b Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 140 Bloom’s Category: 2. Understanding 58. Which of the following statements is false? a. Calcium ions can stimulate their own release from intracellular stores. b. The opening of calcium channels takes place relatively slowly, from seconds to minutes. c. Calcium ions can act as second messengers. d. The entry of a sperm into an egg causes a massive opening of calcium channels. e. Increases in calcium can result in the activation of protein kinase C. Answer: b Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 140 Bloom’s Category: 4. Analyzing 59. Viagra, used to treat erectile dysfunction, acts by means of the release of the second messenger a. cyclic AMP. b. calcium ion. c. nitric oxide. d. calmodulin. e. acetylcholine. Answer: c Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 140 Bloom’s Category: 2. Understanding 60. Which of the following about nitric oxide is true? a. Because it is chemically stable, it is able to travel relatively long distances. b. It does not diffuse readily. c. It is released by nitroglycerin, resulting in the relaxation of blood vessels. d. Calcium ions inhibit the enzyme that catalyzes nitric oxide. e. All of the above Answer: c Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 140 Bloom’s Category: 2. Understanding 61. Increased synthesis of phosphodiesterase would lead to a. decreased concentration of cyclic AMP. b. increased concentration of cyclic AMP. c. increased concentration of calmodium. d. decreased concentration of calmodium. e. inhibition of adenylyl cyclase. Answer: a Textbook Reference: 7.3 How Is the Response to a Signal Transduced through the Cell? Page: 141 Bloom’s Category: 3. Applying 62. Which of the following statements is true? a. Some mammals have over 1,000 genes for odor signal receptors. b. The signal transduction pathway triggered by odorant molecules results in the opening of ion channels. c. Each of the thousands of neurons in the nose expresses one of the odor signal receptors. d. Odorant receptors are G protein-linked. e. All of the above Answer: e Textbook Reference: 7.4 How Do Cells Change in Response to Signals? Page: 142 Bloom’s Category: 2. Understanding 63. Which of the following is not involved in the signaling cascade after the odorant molecule binds to its receptor? a. Activation of a G protein b. Cyclic AMP used as a second messenger c. Nitric oxide used as second messenger d. Gated opening of ion channels e. All of the above are involved in the signaling cascade. Answer: c Textbook Reference: 7.4 How Do Cells Change in Response to Signals? Page: 143 Bloom’s Category: 2. Understanding 64. 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 Answer: b Textbook Reference: 7.4 How Do Cells Change in Response to Signals? Page: 143 Bloom’s Category: 4. Analyzing 65. The G protein-mediated cascade stimulated by epinephrine results in the phosphorylation of two key enzymes. The eventual results of this phosphorylation are the _______ of glycogen synthase and the _______ of glycogen phosphorylase. a. stimulation; stimulation b. stimulation; inhibition c. inhibition; stimulation d. inhibition; inhibition e. inhibition; introversion Answer: c Textbook Reference: 7.4 How Do Cells Change in Response to Signals? Page: 143 Bloom’s Category: 2. Understanding 66. Which of the following statements about gap junctions is true? a. They generally occupy less than 5 percent of the area of the plasma membrane. b. They are specialized structures that permit metabolic cooperation among the linked cells. c. They occur only in plants. d. They are made of G proteins. e. All of the above Answer: b Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 144 Bloom’s Category: 2. Understanding 67. Which of the following statements is true? a. Most cells are in contact with their neighbors. b. Tight junctions are specialized for intercellular communication. c. Desmosomes are specialized for intercellular communication. d. Gap junctions are channels between adjacent cells. e. All of the above Answer: a Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 144 Bloom’s Category: 2. Understanding 68. Which of the following are specialized cell junctions that allow neighboring cells to communicate directly? a. Tight junctions b. Gap junctions c. Desmosomes d. Ion channels e. G proteins Answer: b Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 144 Bloom’s Category: 1. Remembering 69. Gap junctions transverse the gap between plasma membranes of two cells by means of a. plasmodesmata. b. desmosomes. c. connexons. d. cyclic AMP. e. direct transduction. Answer: c Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 144 Bloom’s Category: 2. Understanding 70. In gap junctions, the channel pores permit the transport of a. small signal molecules. b. ions. c. proteins. d. Both a and b e. All of the above Answer: d Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 144–145 Bloom’s Category: 1. Remembering 71. Which of the following statements about plasmodesmata is false? a. Plasmodesmata are lined by the fused membranes themselves. b. Plasmodesmata are larger than a gap junction channel. c. The desmotubule is probably derived from the endoplasmic reticulum. d. Only small metabolites and ions can move between plant cells. e. Plasmodesmata are specialized for intercellular communication. Answer: e Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 144–145 Bloom’s Category: 2. Understanding 72. The membrane-lined bridges spanning the cell walls between plant cells are known as a. gap junctions. b. tight junctions. c. plasmodia. d. plasmodesmata. e. G protein receptors. Answer: d Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 145 Bloom’s Category: 1. Remembering 73. Which of the following is a similarity of animal and plant cells? a. The connections between cells in both are lined by the fused plasma membranes themselves. b. The space available for diffusion is about the same in both. c. Both have tiny circulatory vessels (capillaries) to bring gases and nutrients to every cell. d. All of the above e. None of the above Answer: b Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 145 Bloom’s Category: 4. Analyzing 74. Which of the following statements about plasmodesmata is true? a. They are not merely passive channels, but can be regulated. b. They are derived from integral proteins from adjacent plasma membranes. c. Their diameter is much smaller than that of a gap junction. d. Large proteins can move between plant cells because of them. e. All of the above Answer: a Textbook Reference: 7.5 How Do Cells Communicate Directly? Page: 145 Bloom’s Category: 2. Understanding