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Question 1

In the development of the nervous system, which is the correct order of events?

a) First, cells must be specified to be neurons, second, these neurons must make connections with their targets, third, the neurons must migrate to their final position, and fourth, the neurons refine their synaptic connections.

b) First, cells must be specified to be neurons, second, the neurons must migrate to their final position, third, these neurons must make connections with their targets, and fourth, the neurons refine their synaptic connections.

c) First, cells must migrate to their final position, second, these cells must be specified to be neurons, third, the neurons must make connections with their targets, and fourth, the neurons refine their synaptic connections.

d) First, the prospective neurons must make connections with their targets, second, the neurons refine their synaptic connections, third, the neurons must migrate to their final position, and fourth, the cells are specified to become neurons.

e) There is no fixed order of events; different portions of the nervous system do things in different ways.

Question 2

In Drosophila, the neurectoderm is located ventrally during gastrulation, while in mice or frogs, the neurectoderm is located dorsally. Which statement best describes how the two systems are similar or different?

a) There are no similarities between flies and vertebrates in development of the nervous system.

b) Although gastrulation is completely different in invertebrates and vertebrates, the formation of a neural tube is identical in the two types of animals.

c) There is little similarity, since the neurectoderm of invertebrates forms their nervous system with no further morphological changes, while in vertebrates, the neural tube forms a bundle of neurons running along the antero-posterior axis called the spinal cord.

d) Although the invertebrate nervous system is a ventrally located nerve cord, and the vertebrate spinal cord is located dorsally, homologous genes play a role, and neurons are ultimately specified through a process of lateral inhibition in both cases.

e) The development of the nervous system in vertebrates and invertebrates is a good example of how evolution can accomplish the same goal, a nervous system, in two completely different ways.

Question 3

How does lateral inhibition work to specify individual neurons in the neural epithelium of invertebrates and vertebrates?

a) Prospective neurons first arise in a cluster, but then, by chance, one cell will come to signal more strongly through Delta and Notch than its neighbors and become the only neuron in the cluster, by inhibiting its neighbors' specification as neurons.

b) Stripes of prospective neurons will inhibit formation of neurons in stripes lateral to themselves.

c) A gradient of inhibition spreads from the cells lateral to the neural epithelium, inhibiting their specification of neurons until a threshold is reached, at which point a single neuron is permitted to develop.

d) Only one cell in each cluster of prospective neurons is fated to become a neuron, and it does so by inhibiting neural development in its lateral neighbors.

e) The epidermal cells in the neural epithelium inhibit the laterally adjacent cells from being epidermis, thus promoting neuronal identity.

Question 4

The ventricular proliferative zone is:

a) a region of cell division in the neural plate.

b) a region of cell division in Henson's node.

c) a region of cell division in the neurectoderm of Drosophila.

d) a region of cell division in the neural tube.

e) none of the above.

Question 5

What is the relationship between dorso-ventral patterning of the neural tube and patterning of the somites?

a) The somites pattern the neural tube after they form.

b) The neural tube plays the role of organizer in being the sole influence on patterning in the somites.

c) Sonic hedgehog from the notochord and floorplate of the neural tube confers ventral fates on both the neural tube and the somite, while BMPs confer more dorsal fates.

d) Both the neural tube and the somites acquire their dorso-ventral patterning during gastrulation.

e) Signals from the node pattern the neural tube and the somites along their dorso-ventral axes as they form.

Question 6

What role, if any, do Hox genes play in specification of neuronal fate?

a) Different Hox genes are activated along the dorso-ventral axis by the gradient of Shh.

b) Different combinations of Hox genes specify the identities of neurons along the antero-posterior axis.

c) Hox genes determine the identity of the segments along the axis of the vertebrate spinal cord.

d) Hox genes determine the different subtypes of neurons that form along the dorso-ventral axis.

e) Hox genes play no role in nervous system development.

Question 7

What is the role of semaphorins and Eph ligands in development of the nervous system?

a) The semaphorins and Eph ligands are growth factors that stimulate cell division of neurons.

b) The semaphorins and Eph ligands act as signals for the outgrowth of neuronal growth cones; in general, both lead growth cones to turn away.

c) The semaphorins and Eph ligands act as signals for the outgrowth of neuronal growth cones; in general, both lead growth cones to come toward them.

d) The semaphorins and Eph ligands are cell-cell adhesion molecules that bind adjacent neurons together.

e) The semaphorins and Eph ligands are cell surface receptors that mediate neuronal cell responses to their microenvironment.

Question 8

What is the consequence for the ability of motor neurons to find their correct targets, if a section of the spinal cord is rotated, so that the antero-posterior axis is reversed?

a) Anterior motor neurons enter the limb in a bundle in the posterior instead of the anterior, but then take novel pathways to find the correct anterior muscles to innervate.

b) Anterior motor neurons enter the limb in a bundle in the posterior instead of the anterior, and follow pathways intended for posterior neurons to make contacts with posterior muscles.

c) Anterior motor neurons change their course to enter the limb in the anterior, but take their usual pathways to find the correct anterior muscles.

d) The motor neurons grow over to the other side of the spinal cord and resume their normal pathways into muscles on their normal side of the body.

e) The neurons fail to make the right connections and degenerate.

Question 9

What does the experiment in which a frog's eye is rotated tell us about the spatial relationships between the retina and the tectum?

a) When the right retina makes connections to the right tectum, nasal (anterior) neurons go to the anterior tectum, and temporal (posterior) neurons go to the posterior tectum.

b) When the right retina makes connections to the right tectum, nasal (anterior) neurons go to the posterior tectum, and temporal (posterior) neurons go to the anterior tectum.

c) When the right retina makes connections to the left tectum, nasal (anterior) neurons go to the posterior tectum, and temporal (posterior) neurons go to the anterior tectum.

d) When the right retina makes connections to the left tectum, nasal (anterior) neurons go to the anterior tectum, and temporal (posterior) neurons go to the posterior tectum.

e) The right and left retina first make connections to each other, the send axon bundles to both the right and left tectum.

Question 10

The 'synaptic cleft' of a neuromuscular junction is:

a) a groove in the muscle cell plasma membrane through which neurons grow.

b) that portion of the cell surface receptor molecule on the surface of a muscle cell, into which the ligand binds.

c) a depression at the end of an axon from which neurotransmitters are secreted.

d) the space between the plasma membrane of a neuron on the pre-synaptic side of the synapse, and the plasma membrane of the muscle cell on the post-synaptic side of the synapse.

e) an opening in the plasma membrane of a muscle cell through which neurotransmitters can enter the muscle cell during neuronal stimulation.

Question 11

Do neurons make synapses with other neurons?

a) No, the only role of neurons is to cause muscles to contract.

b) No, neurons can enervate tissues other than muscle, but there is no need for them to enervate other neurons.

c) Yes, neurons make contacts with other neurons that are identical to those they make with muscle cells.

d) Yes, however, the connections neurons make with each other differ from those they make with muscle cells in that cell-cell adhesion molecules link the pre-synaptic and post-synaptic membranes together.

e) Yes, neurons make a special contact with other neurons in which axons form synapses exclusively with other axons.

Question 12

Why can't babies see well when they are first born?

a) The multiple connections between the retina and the visual cortex present at birth become refined in response to visual stimuli, through changes in connectivity and cell death.

b) At birth, the eyes are not yet connected to the visual cortex, and processing of visual stimuli occurs only at the level of the geniculate nucleus.

c) Synapses have formed at birth, but are not functional until visual stimuli begin to occur.

d) The lens of the eye is not fully formed at birth.

e) Their eyes aren't open when they are first born!

Oxford University Press, Online Resource Centre, Chapter 10.

Chapter 10

Instructions