N152+Final+Exam+KEY-2

N152+Final+Exam+KEY-2 - Name: _ Bio Sci N152 Final Exam...

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Name: ___________________________________ Bio Sci N152 Final Exam Student ID: _______________________________ 1. Pioneer axons a. are the first axons laid down b. navigate through a more simple environment than the axons of later-born neurons c. guide the formation of axonal pathways d. use local cues, such as guidepost cells, to find their way e. all of the above 2. Hibbard’s experiments in which he rotated a piece of the embryonic salamander hindbrain and examined the axonal projections of Mauthner cells demonstrated that a. axon navigation is controlled by an intrinsic program of directions in the axon b. axons never find their appropriate targets if the position of their cell bodies is re- oriented c. axons rely on local, extrinsic cues to find their targets d. axons normally make many errors on their journey to their targets e. axons cannot adjust their trajectories during development 3. Growth cones are __________ to their environment and __________ are necessary to guide them. a. insensitive; myosin filaments b. insensitive; actin filaments c. sensitive; myosin filaments d. sensitive; actin filaments e. neutral; myosin filaments 4. During development, netrin serves as a. a long-range cue b. a short-range cue c. an attractant d. a repellent e. all of the above 5. Axon fasciculation is an example of a. contact-mediated axon guidance b. long-range chemoattraction c. long-range chemorepulstion d. short-range contact repulsion e. none of the above 6. Which of the following statements regarding long-range axon guidance is TRUE? a. molecular guidance cues must not be diffusible b. long-range molecular guidance cues are only repulsive c. long-range molecular guidance cues are only attractive d. the growth cone must express the proper receptors to detect the molecular guidance cue e. none of the above 1
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7. Growth cone responses to extracellular cues are mediated by localized changes in intracellular a. [Cl - ] b. [Na + ] c. [K + ] d. [Ca 2+ ] e. [Mg 2+ ] 8. Which of the following controls dendrite morphology? a. neurotrophins b. neuronal activity c. cell adhesion molecules d. semaphorins e. all of the above 9. Axon branching a. is dynamic b. is mediated by changes in the actin and microtubule cytoskeleton c. is often followed by selective axon branch elimination d. all of the above e. none of the above 10. Defasciculation a. usually occurs after synapse formation in the central nervous system b. is not affected by the target of the axons c. is mediated by the balance between pro- and anti-adhesive factors d. is an important process in dendritic branching e. all of the above 11. For sympathetic neurons, target recognition is mediated by the expression of a. neurotrophins b. Ephs and ephrins c. fibroblast growth factors (FGFs) d. Wnts e. Sonic hedgehogs (Shhs) 12. If the optic nerve of a frog is cut and the detached eye is rotated 180 degrees, then the optic nerve axons grow to a. their original targets b. the targets corresponding to the eye’s current (rotated) position
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N152+Final+Exam+KEY-2 - Name: _ Bio Sci N152 Final Exam...

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