Developmental Neurobio Final Review

Which of the following factors are expressed more in forebrain and midbrain than in hindbrain in a wild type //Drosophila// embryo? a) Wnt1 b) FGF8 c) Otx2 d) Gbx2

(a) Wnt1 (b) FGF8

Which of the following statements describing experiments with //C. elegans// is FALSE? a) //C. elegans// is a useful model organism because it has a rapid life cycle, is mostly transparent and causes important human diseases. b) With only 1000 cells, it has been possible to follow the mitotic lineage of every cell during development of //C. elegans//. c) Mosaic specification of cell fate describes how the fate of every cell in //C. elegans// is specified by mitotic lineage and does not seem to depend on any outside influences. d) The cell fate of each daughter cell produced after the initial cell division is determined by different distributions of maternal transcription factors in the egg. e) Unc-86, mec-3, and SKN-1 are all transcription factors that are transcribed in the nucleus but translated in the cytosol.

(a) //C. elegans// is a useful model organism because it has a rapid life cycle, is mostly transparent and causes important human diseases.

Which is FALSE about sight in humans? *Choose ALL that apply.* a) Amblyopia refers to visual impairments caused by defects in the retina. b) It's best to wait until adolescence to perform surgery on a child with strabismus so their eyes have fully developed. c) The sensitive period for vision corresponds to when RGCs grow towards the LGN. d) Humans who are born blind and regain sight within the first few months of life can usually see quite well. e) When people are born blind and have sight restored in adulthood, it is hard to recognize objects and faces visually. f) Binocular vision is fully restored when strabismus is corrected in adults.

(a) Amblyopia refers to visual impairments caused by defects in the retina. (b) It's best to wait until adolescence to perform surgery on a child with strabismus so their eyes have fully developed. (c) The sensitive period for vision corresponds to when RGCs grow towards the LGN. (f) Binocular vision is fully restored when strabismus is corrected in adults.

Sensory neurons all require target-derived neurotrophins in order to survive. Match the neurotrophins to their respective sensory neurons. a) BDNF b) NT3 c) NGF d) NT4/5 - Lower motor neurons - Pain neurons - Neurons innervating hair follicles - Proprioceptive neurons - Touch neurons

(a) BDNF - touch neurons (b) NT3 - proprioceptive neuron (c) NGF - pain neurons (d) NT4/5 - neurons innervating hair follicles

Which of the following is FALSE about Fragile X syndrome? *Choose ALL that apply.* a) CGG repeats in the FMR1 gene cause increased numbers of arginine amino acids in the FMR1 protein. b) Sometimes a child will have more CGG repeats than a parent because there is expansion (anticipation) in the gametes. c) Symptoms of FXS include autism, intellectual disability, low muscle tone, and elongated face. d) FXS is an example of redundancy. e) Wild-type FMR1 protein acts to repress translation of proteins. f) FMR1 KO mice are good animal models of FXS and neurons in these mice have too many spines.

(a) CGG repeats in the FMR1 gene cause increased numbers of arginine amino acids in the FMR1 protein. (d) FXS is an example of redundancy.

Which of the following animals are likely to show mounting (male) behavior? *Choose ALL that apply.* a) Control untreated males b) Control untreated females c) Males deprived of testosterone at birth d) Females given testosterone perinatally e) Females given testosterone at puberty f) Females given testosterone perinatally and at puberty

(a) Control untreated animals (f) Females given testosterone perinatally and at puberty

Which of the following is true? *Choose ALL that apply.* a) NMDA receptors are blocked by an Mg2+ ion at resting membrane potential. b) Ca2+ ions flowing into the cell through the NMDA receptor can activate kinases. c) CAMKII activation leads to endocytosis of AMPA receptors. d) CREB is a transcription factor e) AMPA is a metabotropic glutamate receptor. f) Hebbian plasticity was first demonstrated at the synapses between perforant pathway neurons and dentate gyrus neurons in rabbits.

(a) NMDA receptors are blocked by an Mg2+ ion at resting membrane potential. (b) Ca2+ ions flowing into the cell through NMDA receptors can activate kinases. (d) CREB is a transcription factor. (f) Hebbian plasticity was first demonstrated at the synapse between perforant pathway neurons and dentate gyrus neurons in rabbits.

Which of the following is true? a) Tectal expansion occurs when half the retina is removed. b) Tectal expansion occurs when half the tectum is removed. c) In frogs, like in mammals, optic nerves are CNS neurons that cannot regenerate in adults. d) Retinotectal projections are more precise when TTX is applied.

(a) Tectal expansion occurs when half the retina is removed.

Which of the following is TRUE about RGCs in frogs? *Choose ALL that apply.* a) The optic nerve consists of axons of RGCs. b) RGCs in frogs can regenerate well, but mammalian RGCs do not regenerate. c) RGCs in the nasal retina innervate anterior tectum. d) Posterior tectum cells express high levels of ephrin receptors. e) Temporal RGCs express high levels of ephrins.

(a) The optic nerve consists of axons of RGCs. (b) RGCs in frogs regenerate well, but mammalian RGCs do not regenerate.

Suppose you make a mutant where Diablo doesn't bind to IAPs. What would you expect to see? a) Increased apoptosis b) Decreased apoptosis c) Higher [Ca2+] inside mitochondria. d) High levels of activated Bcl-2 proteins. e) Activation of caspases.

(b) Decreased apoptosis

The spinal nucleus of the bulbocavernosus (SNB) contains lower motor neurons (LMN) that innervate muscles at the base of the penis. This nucleus is the same size in males and females during development, but many of the neurons die in females. Testosterone produced in males during development prevents apoptosis of these neurons. Many experiments were performed to study this effect of testosterone. Which of the following rodents will have a large SNB? Unless otherwise stated, the ARKO animals are homozygous KOs. *Choose ALL that apply.* a) wild type female rats treated with testosterone during development b) wild type male rats c) male ARKO rats d) female ARKO rats e) female ARKO rats treated with testosterone during development f) male cre-lox mice that have AR removed from motor neurons g) male cre-lox mice that have AR removed from muscle fiber cells h) male cre-lox mice that have AR removed from muscle mesenchymal cells

(a) wild type female rats treated with testosterone during development (b) wild type male rats (f) male cre-lox mice that have AR removed from motor neurons (g) male cre-lox mice that have AR removed from muscle fiber cells

Which of the following would be useful as labels to determine cell birthdates? *Choose all that apply.* a) 14C-uridine b) 14C-thymidine c) 3H-thymidine d) 3H-cytosine e) Thymidine f) 3H-uridine g) 5-bromo-2-deoxy-uridine h) Uridine

(b) 14C-thymidine (c) 3H-thymidine (g) 5-bromo-2-deoxy-uridine

Which of the following is FALSE about embryonic development in //Drosophila//? *Choose ALL that apply.* a) Cell division doesn't happen until after expression of pair-rule genes. b) A mutant //nanos// gene that produced a non-functioning nanos protein would lead to a fly embryo with 2 tail regions. c) Injection of //bicoid// mRNA into the posterior end of wild type fly embryos caused the formation of 2 head regions. d) Bicoid and nanos are transcription factors that are synthesized in the nucleus and never reach the cytoplasm.

(b) A mutant //nanos// gene that produced a non-functioning nanos protein would lead to a fly embryo with 2 tail regions. (d) Bicoid and nanos are transcription factors that are synthesized in the nucleus and never reach the cytoplasm.

Which of the following is FALSE? *Choose all that apply.* a) The //Drosophila// homolog of human Hox C5 is //scr//. b) All transcription factors are homeobox genes. c) Every //Drosophila// Hox gene has 4 human homologs (one each on chromosomes 2, 7, 12 & 17) d) The fact that there is more redundancy in mammalian Hox genes than in fly Hox genes is due partially to gene duplication during evolution.

(b) All transcription factors are homeobox genes. (c) Every //Drosophila// Hox gene has 4 human homologs (one each on chromosomes 2, 7, 12 & 17)

In the developing flye eye, which of the following statements are TRUE? *Choose ALL that apply.* a) A cascade of transcription factors, including Hh, direct the forward motion of the morphogenetic furrow. b) An RTK has hydrophobic amino acids in its transmembrane sequences. c) Each ommatidium contains 8 photoreceptor cells. d) R8 directs the fate R1 - R6 cells via the diffusible signaling factor sevenless. e) An ommatidium in the wake of the morphogenetic furrow will have most of the photoreceptor cells differentiated, while an ommatidium ahead of the furrow will have undifferentiated photoreceptor neurons. f) The gene for Hh has the sequence for a signal peptide on it. Signal peptides are a classic motif found in all transcription factors. g) R1 differentiates first and R8 matures last. h) The cell that becomes R8 is determined by cell-cell contact signaling.

(b) An RTK has hydrophobic amino acids in its transmembrane sequences. (c) Each ommatidium contains 8 photoreceptor cells. (e) An ommatidium in the wake of the morphogenetic furrow will have most of the photoreceptor cells differentiated, while an ommatidium ahead of the furrow will have undifferentiated photoreceptor neurons. h) The cell that becomes R8 is determined by cell-cell contact signaling.

Which of the following are true about neurotrophins? *Choose ALL that apply.* a) NGF was first isolated from snake venom. b) BDNF activates TrkB receptors. c) You would need more NT3 to activate 50% Trk C receptors than to activate 50% p75 receptors. d) All Trks are RTKs, but all RTKs are Trks. e) Nodose ganglia have Trk B & Trk C receptors, but not Trk A receptors. f) Post-ganglionic sympathetic neurons have more Trk B receptors than Trk A receptors.

(b) BDNF activates Trk B receptors. (d) All Trks are RTKs, but not all RTKs are Trks. (e) Nodose ganglia have Trk B & Trk C receptors but not Trk A receptors.

Which of the following are examples of pleiotropy? *Choose ALL that apply.* a) BDNF knockouts have slightly smaller nodose ganglia (cell bodies of the vagus nerve) than wild type and neurotrophin-4 (NT4) knockouts have slightly smaller nodose ganglia than wild type. However, double knockouts of BDNF and NT4 have no nodose ganglia at all. b) BMP is important for differentiation of epithelial cells, for dorsal/ventral patterning in the spinal cord and for bone development. c) While noggin knockout mice or chordin knockout mice have some brain abnormalities, double knockouts of noggin and chordin have no brain. d) Shh affects dorsal/ventral development of the spinal cord as well as inhibiting the midline of the telencephalon so that 2 optic cups form.

(b) BMP is important for differentiation of epithelial cells, for dorsal/ventral patterning in the spinal cord and for bone development. (d) Shh affects dorsal/ventral development of the spinal cord as well as inhibiting the midline of the telencephalon so that 2 optic cups form.

Which of the following are TRUE statements about cerebellar development? *Choose ALL that apply.* a) Granule cells migrate dorsally from the 4th ventricle. b) Bergmann glia are specialized astrocytes. c) Purkinje cells migrate from the rhombic lip. d) If you mix glia from weaver mice with wild type granule cells, migration occurs normally. e) External granule cells in reeler mice remain outside (on the pial side) of Purkinje cell bodies. f) Purkinje cells migrate along parallel fibers.

(b) Bergmann glia are specialized astrocytes. (d) If you mix glia from weaver mice with wild type granule cells, migration occurs normally. (e) External granule cells in reeler mice remain outside (on the pial side) of Purkinje cell bodies.

Which of the following signaling molecules acts by inhibiting protein kinase A? a) Hox C5 b) Otx2 c) Shh d) BMP4 e) Retinoic acid f) Wnt7a g) FGF8

(c) Shh

Which of the following statements is FALSE? a) When pioneer neurons in grasshoppers reach cells expressing semaphorins, it causes growth cone collapse. b) Fasciculation refers to the growth of individual pioneer neurons. c) Growth cones expressing robo are repelled by split. d) Knockout of either robo or slit causes axons to keep circling around the midline. e) Overexpression of robo prevents neurons from crossing the midline.

(b) Fasciculation refers to the growth of individual pioneer neurons.

Which of these diseases does NOT involve demyelination? a) Multiple sclerosis b) Fragile X syndrome c) Gullain-Barre syndrome d) Marie-Charcot-Tooth diseases

(b) Fragile X syndrome

Which of the following statements is TRUE? a) Sponges and jellyfish are some of the first protozoans that appeared on earth. b) In a mammal, the genotype of an individual remains the same while the phenotype changes as an individual ages. c) The nerve net of jellyfish is only capable of simple reflexes. d) Mendel's result proved that the theory of pre-formation was correct.

(b) In a mammal, the genotype of an individual remains the same while the phenotype changes as an individual ages.

Which is false of ion channels and developing synapses? a) Ligand-gated ion channels are activated by intracellular or extracellular ligands. b) In embryonic neurons depolarization of action potentials is driven by efflux of Ca2+. c) In immature neurons, GABA can cause depolarization because the intracellular [Cl-] is higher than the extracellular [Cl-]. d) As neurons mature the amplitude of EPSPs and IPSPs remains the same. e) As neurons mature the time-course of EPSPs and IPSPs becomes shorter.

(b) In embryonic neurons depolarization of action potentials is driven by efflux of Ca2+.

Which is TRUE about growth cones? *Choose ALL that apply.* a) Growth cones grow by extending long slender rod-like lamellipodia to test the environment. b) Microtubules are important for structure of the growing axon as well as axonal transport. c) Transport of building materials from the cell body to the growth cone is called retrograde transport. d) Filopodia contain F-actin attached to actin-binding proteins at the membrane. e) Axons extend by adding more microtubules at the growth cone end of the growing axon. f) Growth cones grow fastest along the most adhesive molecules.

(b) Microtubules are important for structure of the growing axon as well as axonal transport. (d) Filopodia contain F-actin attached to actin-binding proteins at the membrane. (e) Axons extend by adding more microtubules at the growth cone end of the growing axon.

Which of the following are found in the post-synaptic terminal? Include any proteins found in both the pre- and post-synaptic terminals. *Choose ALL that apply.* a) Neurexin b) Neuroligin c) PSD95 d) Synaptotagmin e) Syntaxin f) SNAP-25 g) NMDAR h) Actin i) MAGUKs

(b) Neuroligin (c) PSD95 (g) NMDAR (h) Actin (i) MAGUKs

Which of the following are FALSE? *Choose ALL that apply.* a) In adult rats, each Purkinje cell is innervated by one climbing fiber from a single inferior olive cell. b) Retraction of axons from a poly-innervated muscle fiber or Purkinje cell is a random process. c) Synapse elimination in the NMJ is accelerated by tetrodotoxin, which blocks Na+ channels. d) Asynchronous action potentials drive synapse elimination. e) Alpha-bungarotoxin (blocks AChRs) applied to a part of an NMJ causes axon withdrawal from that area. f) In autonomic ganglia, as polyneuronal innervation is eliminated, the one remaining afferent increases the number of synapses.

(b) Retraction of axons from a poly-innervated muscle fiber or Purkinje cell is a random process. (c) Synapse elimination in the NMJ is accelerated by tetrodotoxin, which blocks Na+ channels.

Which of the following is TRUE about BMP signaling? *Choose ALL that apply.* a) BMPs are part of a family of TGF-beta receptors. b) TGF-beta receptors are transmembrane molecules. c) Noggin and chordin are both BMP agonists. d) BMP4 is secreted from cells in the notochord. e) BMP4 is synthesized in ectodermal cells.

(b) TGF-beta receptors are transmembrane molecules. (e) BMP4 is synthesized in ectodermal cells.

Which of the following are TRUE? *Choose ALL that apply.* a) Muscle cells release agrin which facilitates aggregation of AChRs. b) The agrin receptors consists of RTK molecules and LRP4. c) Rapsyn is a protein that binds extracellular domains of AChRs to bind them togther. d) The rapsyn complex stabilizes AChRs in the membrane via phosphorylation. e) Depolarization speeds up internalization of unaggregated AChRs and decreases AChR expression. f) Neuregulins bind to and activate GPCR receptors called ErbB. g) Neuregulins cause increased translation of AChRs in subsynaptic nuclei. h) Neuregulins act via their ErbB receptors to promote maturation of the terminal Schwann cell.

(b) The agrin receptors consists of RTK molecules and LRP4. (d) The rapsyn complex stabilizes AChRs in the membrane via phosphorylation. (e) Depolarization speeds up internalization of unaggregated AChRs and decreases AChR expression.

Which of the following is true about 3-eyed frogs? *Choose ALL that apply.* a) The extra eye innervated ipsilateral and contralateral tectum in equal amounts. b) The extra eye and the normal eye on the same side innervated isolated bands of contralateral tectum. c) The eye on the side opposite to the extra eye innervated the same part of tectum as the extra eye. d) Radiolabeled amino acids or horseradish peroxidase could be used as a label to map retinotectal projections. e) TTX causes more rapid segregation of tectal inputs. f) Inhibition of NMDA receptors abolished segregation of tectal inputs. g) Visual input even in adult frogs can drive fine tuning of tectal inputs.

(b) The extra eye and the normal eye on the same side innervated isolated bands of contralateral tectum. (d) Radiolabeled amino acids or horseradish peroxidase could be used as a label to map retinotectal projections. (f) Inhibition of NMDA receptors abolished segregation of tectal inputs. (g) Visual input even in adult frogs can drive fine tuning of tectal inputs.

Which is true about innervation of the right LGN? *Choose ALL that apply.* a) The right LGN only receives input from the left eye. b) The right LGN only receives input from the left visual field. c) The right LGN receives input from nasal RGCs in the right eye. d) The right LGN receives input from nasal RGCs in the left eye. e) The right LGN receives input from temporal RGCs in the left eye. f) The right LGN receives input from temporal RGCs in the right eye.

(b) The right LGN only receives input from the left visual field. (d) The right LGN receives input from nasal RGCs in the left eye. (f) The right LGN receives input from temporal RGCs in the right eye.

Which of the following would happen in the primary somatosensory if you remove a row of whiskers from a mouse at birth? *Choose ALL that apply.* a) Whisker barrels for the removed whiskers will be unchanged. b) Whisker barrels for the removed whiskers will be lost. c) Whisker barrels for the removed whiskers will be larger. d) Whisker barrels for neighboring whiskers will be unchanged. e) Whisker barrels for neighboring whiskers will be lost. f) Whisker barrels for neighboring whiskers will be larger.

(b) Whisker barrels for the removed whiskers will be lost. (f) Whisker barrels for neighboring whiskers will be larger.

Which of the following statements is TRUE about cell division in the neural tube? a) Neurogenesis is the process by which neurons divide to form new neurons. b) When cells in the neural tube divide symmetrically, one of the post-mitotic cells losses its attachment to both pial and ventricular surfaces. c) As cells accumulate near the pial surface, this becomes the marginal zone. d) The pial surface of the neural tube will end up lining the ventricles in the adult brain.

(c) As cells accumulate near the pial surface, this becomes the marginal zone.

Which is true about apoptosis? *Choose ALL that apply.* a) More apoptosis occurs in the webbed skin between duck digits than between chick digits. b) Cells undergoing apoptosis swell and burst, leaking their contents into the surrounding tissue. c) Bcl-2 is an anti-apoptotic protein. d) Caspase 9 is an initiator caspase. e) Caspase 9 acts by cleaving proteins such as endonucleases, which then cleave DNA. f) Caspase 9 KOs died because there was far more neurogenesis than in wild type controls.

(c) Bcl-2 is an anti-apoptotic protein. (d) Caspase 9 is an initiator caspase.

Which of the following undergoes homophilic binding to increase adhesion between developing pre-and post-ganglionic neurons? a) Ephrins b) N-CAM c) Cadherins d) Catenins e) Laminins

(c) Cadherins

Which is true about development of sensory pathways? *Choose ALL that apply.* a) Neurons in the owl tectum respond only to either visual or auditory stimuli. b) Olfactory receptors are G-proteins. c) Mice have more than twice as many functional olfactory receptor genes than humans. d) Olfactory sensory neurons (OSNs) expressing more than one OR usually die by apoptosis. e) If you close a nostril then OSNs containing more than one OR die faster in that nostril than in the unblocked nostril. f) Axons on OSNs expressing one particular OR converge onto two glomeruli in the olfactory bulb (OB). g) Competition within the OB causes inactive OSNs to die.

(c) Mice have more than twice as many functional olfactory receptor genes than humans. (d) Olfactory sensory neurons (OSNs) expressing more than one OR usually die by apoptosis. (f) Axons on OSNs expressing one particular OR converge onto two glomeruli in the olfactory bulb (OB). (g) Competition within the OB causes inactive OSNs to die.

Which of the following is false about the developing NMJ? a) The active zone in the pre-synaptic terminal sits opposite junctional folds in the post-synaptic muscle cell. b) Motor neurons release acetylcholine from growth cones. c) Nicotinic AChRs are concentrated in the pre-synaptic terminal. d) Layers of ECM molecules called the basal lamina lie between a muscle cell and a MN. e) Terminal Schwann cells surround the NMJ.

(c) Nicotinic AChRs are concentrated in the pre-synaptic terminal.

Which cortex develops last? a) Primary visual b) Primary auditory c) Pre-frontal d) Primary somatosensory

(c) Pre-frontal

Which of the following signaling molecules can diffuse through cell membranes? a) BMPs b) FGFs c) Retinoic acid d) BMP antagonists, like noggin e) Wnts f) Ephrins

(c) Retinoic acid

Which statements about myelin are true? *Choose ALL that apply.* a) Individual Schwann cells myelinate multiple axons. b) Individual oligodendrocytes myelinate one axon. c) Schwann cells myelinate PNS while oligodendrocytes myelinate CNS. d) Nogo is expressed on astrocytes. e) Oligodendrocytes from a glial scar that prevents regeneration in the CNS. f) Myelin mostly consists of lipid bilayers containing phospholipids, cholesterol, and with proteins such as MPB. g) Multiple sclerosis is a disease where both CNS and PNS myelin is degraded.

(c) Schwann cells myelinate PNS while oligodendrocytes myelinate CNS. (f) Myelin mostly consists of lipid bilayers containing phospholipids, cholesterol, and with proteins such as MPB.

Which of the following statements is FALSE? a) The intermediate zone in cerebral cortex becomes white matter. b) Purkinje cell bodies lie between intermediate and marginal zones in the cerebellum c) The external granule layer (EGL) in the cerebellum forms when cells of the internal granule layer (IGL) migrate through the Purkinje cell layer. d) In the VZ, only asymmetric cell division occurs while in the SVZ, both asymmetric and symmetric cell division occurs. e) Layer V pyramidal cells in the cerebral cortex are part of the cortical plate.

(c) The external granule layer (EGL) in the cerebellum forms when cells of the internal granule layer (IGL) migrate through the Purkinje cell layer.

What is the difference between, for example, a skin cell and a muscle cell? *Choose ALL that apply.* a) The sequence of A, C, G, and T bases in the genome. b) The localization of DNA in the cells. c) The proteins made in the cells. d) The transcription factors expressed in the cells. e) The localization of protein synthesis in the cells. f) The genetic code in the cells.

(c) The proteins made in the cells; (d) The transcription factors expressed in the cells.

Which of the following statements is correct about neuromuscular junctions (NMJs)? a) Curare (AChR antagonist) causes apoptosis of MNs. b) A motor unit is one muscle fiber and the several MN that innervate it. c) In adult rats, increasing the electrical stimulation of the nerve causes incremental increases in EPSPs. d) Elimination of polyneuronal innervation occurs after apoptosis of MNs. e) The peak of polyneuronal innervation of muscle fibers occurs postnatally.

(d) Elimination of polyneuronal innervation occurs after apoptosis of MNs.

Which of the following is NOT evidence for late development of the human brain compared to other species? a) After birth, human brains grow proportionally far more than chimpanzee brains. b) The pre-frontal cortex, which is bigger in humans compared to other primates, is the last cortical area to mature. c) The neocortex is bigger in primates compared to rodents, especially in the later to mature layers II and III. d) Humans are more intelligent than rats and mice because they are more highly evolved.

(d) Humans are more intelligent than rats and mice because they are more highly evolved.

Which of the following is TRUE about motor neurons? a) Motor neurons axons are still attracted ephrins expressed by somite cells. b) Motor neuron cell bodies reside in the dorsal horn of the spinal cord. c) Motor neurons rely entirely on cues outside the spinal cord to reach their target muscles. d) Motor neurons seem to be specified to innervate a particular target even before their axons leave the spinal cord.

(d) Motor neurons seem to be specified to innervate a particular target even before their axons leave the spinal cord.

Which is FALSE about plasticity? a) Plasticity can reinforce or weaken synapses. b) Synapses that are reinforced can grow larger c) When a pre-synaptic neuron doesn't fire much on the post-synaptic neuron, the synapse can disappear d) Plasticity at all synapses involves NMDA receptors e) NMDA receptors act as "and-gates" to mediate LTP f) LTP is likely to be the cellular correlate for memory formation

(d) Plasticity at all synapses involves NMDA receptors

Suppose a cell developing in the neural tube is exposed to the following sequence of signals: Noggin/chordin then less delta expressed than its neighbor, then neuregulin. What will the fate of that cell likely be? a) Sensory neuron b) Motor neuron c) Microglia d) Oligodendrocyte e) Astrocyte

(e) Astrocyte

Which of the following are diffusible molecules that signal to other cells? *Choose all that apply.* a) N-CAM b) L1 c) Cadherins d) RTKs e) Ephrins f) EphRs g) RhoGAPs h) Netrin i) Slit j) Robo k) Frazzled l) Unc-5 m) Plexin n) Semaphorins o) Neuropilin

(h) Netrin (i) Slit (n) Semaphorins

Which of the following molecules are expressed on growth cones of commissural axons? *Choose ALL that apply.* a) Frazzled b) Netrins c) Slit d) Robo

a) Frazzled d) Robo

Which of the following is NOT a symptom of Kallmann syndrome in a male? a) Night blindness b) Lack of smell c) Low [testosterone] d) Partial deafness e) Little or no sperm production

a) Night blindness

Which cell types can be found in developing olfactory placode? *Choose ALL that apply.* a) Mitral cells b) Olfactory ensheathing glia (OEGs) c) GnRH-producing cells d) Neural crest cells e) FSH-producing glia f) Olfactory sensory neurons (OSNs) g) LH-producing cells

b) Olfactory ensheathing glia (OEGs) c) GnRH-producing cells d) Neural crest cells f) Olfactory sensory neurons (OSNs)

Which of the following is FALSE about migration of neural crest cells? *Choose ALL that apply.* a) Neural crest cells that become DRGs migrate a short distance and stop dorsomedial to somites. b) Some neural crest cells stop migrating near the notochord and become adrenal cortex cells. c) In order to migrate neural crest cells undergo a mesenchymal to epithelial transition. d) Neural crest cells down-regulate N-cadherin and tight junction proteins in order to begin migrating. e) Neural crest cells migrate anterior to each somite because ephrins are expressed in posterior somite cells. f) Neural crest cells down regulate N-CAM expression while they migrate.

b) Some neural crest cells stop migrating near the notochord and become adrenal cortex cells. c) In order to migrate neural crest cells undergo a mesenchymal to epithelial transition. f) Neural crest cells down regulate N-CAM expression while they migrate.

Which is true about the "Spemann organizer"? a) The organizer was first identified as tissue positioned at the ventral tip of the blastopore. b) When organizer tissue was placed ectopically it induced the formation of a new newt (albeit, joined to a second newt at the ventral surface). c) When organizer tissue from a pigmented newt was added to the blastula of an unpigmented newt, most of the cells in the newt were pigmented. d) No one ever doubted the experiments of Mangold and Spemann, but it took a long time before the gene for the organizer was discovered.

b) When organizer tissue was placed ectopically it induced the formation of a new newt (albeit joined to a second newt at the ventral surface).

Place the following in the correct order for symptoms of Hansen's disease: a) //Mycobacterium leprae// infects Schwann cells b) The immune system attacks myelin c) Neural crest cells migrate ventrally past the neural tube d) Neural crest cells migrate to skin and become melanocytes e) Schwann cells become dissociated from the damaged axons f) Schwann cells differentiate g) Schwann cells de-differentiate

c, f, a, b, e, g, d

Which of the following statements about gastrulation is TRUE? a) A large blastula develops inside a blastocoel. b) The three germ layers formed at gastrulation are exoderm, mesoderm, and endoderm. c) Muscles and bones are derived from endoderm cells. d) Gastrulation is the process by which an embryo begins to form a primitive gut. e) Neurons and skin cells are derived from mesoderm. f) In mammals, the inner cell mass forms the placenta. g) The primitive streak is on the ventral side of the body.

d) Gastrulation is the process by which an embryo begins to form a primitive gut.

Which of the following statements is NOT true about mosaic versus conditional specification of cell fate? a) Wilhem Roux's experiment suggested a mosaic specification of cell fate. b) Embryonic stem cells are totipotent. c) Once the neural crest has formed, many cells are still pluripotent but most cells in the embryo are not totipotent. d) Mosaic specification of cell fate depends more on cell-cell interactions than condition specification of cell fate. e) The generation of transgenic mice relies on conditional rather than mosaic specification of cell fate. f) Spemann found that optic cup induced lens formation in most overlying epithelium - this is an example of conditional cell fate specification.

d) Mosaic specification of cell fate depends more on cell-cell interactions than condition specification of cell fate.

Which of the following is NOT a neural crest derivative? a) Melanocytes b) Post-ganglionic sympathetic adrenergic neurons c) Primary pain neurons d) Schwann cells e) Lower motor neurons f) Some skin cells in head and neck g) Some cells in salivary glands

e) Lower motor neurons

Place the following cerebral cortical cells in order of their birth, starting with the earliest cells produced first. a) internal granule layer b) external granule layer c) internal pyramidal layer d) external pyramidal layer e) multiform layer

e, c, a, d, b

Place the following in the correct order: i) The notochord forms ventral to the neural groove. ii) Neural crest cells migrate ventrally. iii) Elongated ectodermal cells form the neural plate. iv) Sides of the neural plate rise to form a neural groove. v) The dorsal lips of the neural groove join to form the neural tube.

iii, iv, i, v, ii

Place these genes in the correct order of expression in //Drosophila// embryos: i) Segment polarity genes ii) Pair-rule genes iii) Gap genes iv) Homeotic genes v) Maternal polarity genes

v, iii, ii, i, iv