Deck 4: Developing a Nervous System

Question 1

Neurons differ in shape, size, neurotransmitter usage, ion channel expression, and connectivity. How is neuronal diversity produced?

A) different neurons express different transcription factors
B) different neurons express different genes
C) transcription factors in fertilized eggs are not evenly distributed
D) all of the above

Answer 1

D

Question 2

You are a researcher studying development. In an experiment, you examine the proteins present in the two cells that arise from a single fertilized frog egg. You are most likely to find that

A) the genes found in each cell are different
B) transcription factors and other proteins found in each cell are completely different
C) some transcription factors and proteins are the same; some are different
D) cells don't express transcription factors and other proteins at the two-cell stage of development

Answer 2

C

Question 3

Identical twins can arise from cells that separate from the developing embryo at or before the ______________ stage of development.

Answer 3

blastocyst

Question 4

Which of the following is NOT true of the germ layers that are found during the gastrulation stage of development?

A) mesoderm is between the ectoderm and endoderm
B) the mesoderm gives rise to the nervous system
C) the ectoderm gives rise to the skin
D) the mesoderm gives rise to both the skin and nervous system

Question 5

The Mangold-Spemann experiment showed that development of the nervous system is dependent on

A) signals from the ectoderm
B) signals from the endoderm
C) signals from the mesoderm
D) all of the above

Question 6

In-situ hybridization is a lab technique that allows you to visualize

A) which parts of an embryo express a given RNA transcript
B) the presence of a certain region of DNA in a cell
C) the cells of an embryo that are producing antibodies
D) all of the above

Question 7

The lab technique that uses labeled probes to visualize RNA transcripts is known as _______________________.

Question 8

Using in-situ hybridization, you see differences in coloration patterns between cells at the gastrula stage of development. Which of the following conclusions could you draw from this experiment?

A) the cells contain different proteins
B) the cells contain different transcription factors
C) the cells contain different mRNA transcripts
D) the cells contain different regions of DNA

Question 9

The concept of a neural inducer molecule originated because

A) certain regions of the developing embryo serve as an organizing center
B) in-situ hybridization experiments showed that a few genes are expressed only in the dorsal blastopore lip
C) when two organizing centers are artificially present in an organism, two nervous systems develop
D) all of the above

Question 10

What do the proteins chordin and bone morphogenic protein (BMP) NOT have in common?

A) they are proteins that are secreted outside of cells
B) they are proteins that regulate differentiation of tissues in a developing organism
C) they both promote the development of neural tissue
D) none of the above answers describe characteristics of both proteins

Question 11

Based on the description of chordin's and BMP's functions in the text, what might you expect to happen if chordin was injected into a site away from the dorsal blastopore lip?

A) there would be two sites that begin to differentiate into neural tissue
B) the site of injection would develop into neural tissue rather than the dorsal blastopore lip
C) the dorsal blastopore lip would develop into skin tissue rather than neural tissue
D) all of the above

Question 12

An identical twin results when a cell from a blastopore stage (or earlier) embryo separates and develops on its own. How is it that the left-behind developing embryo can lose a cell and still develop normally?

Question 13

Place the following events in order, with 1 being the first event in the process.
____ formation of neural plate
____ fertilization
____ blastopore
____ formation of neural groove
____ chordin and BMP direct formation of neural tissue and skin tissue
____ formation of neural tube

Question 14

The cell type in development that goes on to form melanocytes, bone cells in the skull, and cranial nerves are the _____________________ cells.

Question 15

The spinal cord develops from the ________________ end of the neural tube.

A) rostral
B) caudal
C) dorsal
D) ventral

Question 16

A candidate molecule for establishing the rostral-caudal organization of the early nervous system is

A) BMP
B) retinoic acid
C) chordin
D) none of the above

Question 17

Based on the text's description of the function of retinoic acid, a deficiency in retinoic acid during development may lead to what types of problems?

A) abnormalities in formation of caudal regions of the nervous system
B) impaired neural crest cell migration
C) cells that become skin rather than neural tissue
D) all of the above

Question 18

Consider figure 4.7. In the text Which of the following statements regarding this figure is true?

A) Hox b-3 gene expression is relatively constant as you move rostrally to caudally in the developing embryo
B) it is possible to visualize protein, but not mRNA, in the developing embryo
C) Segment r4 has a higher degree of Hox a-3 gene expression than r5
D) all of the above are true

Question 19

Consider figures 4.6 and 4.8. In the text Which of the following statements regarding rostral-caudal patterning in the developing nervous system is true regarding the most caudal area of the neural tube?

A) Many Hox genes are expressed and retinoic acid concentrations are high
B) Few Hox genes are expressed and retinoic acid concentrations are high
C) Many Hox genes are expressed and retinoic acid concentrations are low
D) Few Hox genes are expressed and retinoic acid concentrations are low

Question 20

Hox genes are

A) thought to be expressed in response to the presence of retinoic acid
B) found in the same order on the chromosome as the segments they correspond to in the neural tube
C) known to control body segmentation, and control body plans beyond neural tube patterning
D) all of the above

Question 21

Consider figure b4.2. In the text Analyze this figure and select which interpretation below is consistent with the findings.

A) Several genes in fruit flies appear to have duplicated somewhere in their ancestral lineage
B) Nematodes express a greater variety of Hox genes than cephalochordates
C) Each organism contains at least one of each known Hox gene, though some contain duplicates
D) Sea urchins are round; therefore they do not require as many Hox genes to direct development

Question 22

Consider figure b4.2. The text describes several duplication events in mammals, and subsequently genes have been "lost" in each cluster. What does this statement mean? Re-write in your own words.

Question 23

The details of how Hox genes control cell fate are not understood. Two competing theories have arisen about this, the combinatorial Hox code model and the posterior prevalence model. Describe each of these theories and propose an experiment that would allow you to determine which is the better model.

Question 24

Sensory neurons develops from the ________________ section of the neural tube.

A) rostral
B) caudal
C) dorsal
D) ventral

Question 25

A candidate molecule for establishing the dorsal-ventral organization of the early nervous system is

A) BMP
B) SHH
C) chordin
D) none of the above

Question 26

Which of the following is NOT a true statement regarding sonic hedgehog protein (SHH)?

A) it is a ventralizing signal in the developing spinal cord
B) its presence induces gene expression of a number of transcription factors
C) its presence represses gene expression of a number of transcription factors
D) it is found in abundance throughout the developing embryonic spinal cord

Question 27

Consider Figure 4.11. In the text The thalamus is ____________________ to the midbrain.

Question 28

Some proteins that function in organizing development are expressed at different times, with apparently different outcomes. Propose how a protein such as BMP could act to promote skin tissue at one stage, but be a dorsalizing agent in the spinal cord later in development.

Question 29

Why might it be advantageous for an organism to "re-use" a protein for multiple purposes (for example BMP at two different stages of development). Propose a reason for this re-use that would give an organism a selective advantage over an organism that uses a unique protein for each purpose.

Question 30

Choose 4 proteins that are important for nervous system development and organize them into a chart, with the name of the protein in one column, its function in another column, and experimental evidence that supports this function in a third column.

Question 31

FGF8 is thought to be involved in which process?

A) dorsal-ventral patterning of the developing spinal cord
B) rostral-caudal patterning of the developing spinal cord
C) dorsal-ventral patterning of the midbrain and forebrain
D) rostra-caudal patterning of the midbrain and forebrain

Question 32

You design a probe for BMP mRNA to be used for in-situ hybridization experiments. You would expect to be able to visualize this probe in

A) dorsal regions of the developing spinal cord
B) ventral regions of the developing spinal cord
C) rostral regions of the developing forebrain
D) rostral regions of the developing midbrain

Question 33

Which of the following is true of radial cells?

A) They extend processes from the ventricle to the brain's external surface
B) they are capable of cell division
C) they are progenitor cells that give rise to neurons
D) all of the above

Question 34

The process where progenitor cells stop dividing and become neurons is called _________________.

Question 35

You are a researcher studying neurogenesis. You artificially lower the amount of beta-catenin expressed in neural progenitor cells. Which of the following would be likely to result?

A) neurogenesis onset would occur sooner than normal
B) neurogenesis onset would occur later than normal
C) neurogenesis onset would result in less delta-1 being produced
D) neurogenesis onset would occur in skin tissue

Question 36

How might you characterize the patterning of the nervous system with regard to the migration of neurons along radial cells?

A) the nervous system is built from the outside in
B) the nervous system is built from the inside out
C) some parts of the nervous system are built from the inside out; some outside in
D) during neurogenesis, neurons migrate first to the ventricle and then to their final destination

Question 37

A mutation in the reelin gene might lead to

A) problems with rostral-caudal patterning of the spinal cord
B) problems with dorsal-ventral patterning of the spinal cord
C) problems with neurogenesis
D) problems with the formation of radial cells

Question 38

The part of the axon that is involved in chemotactic movement is called the ________________________.

Question 39

Analyze figure 4.20. In the text What is NOT true regarding the process depicted in these photomicrographs?

A) netrin is acting as a chemoattractant
B) filopodia are able to adhere to the culture dish substrate
C) chemoattractants require heating for proper function
D) actin is present in the structure in each of the 4 photomicrographs

Question 40

Axon reprogramming solves a problem that can best be characterized by which of the following questions?

A) How do growth cones extend toward their targets?
B) How do growth cones follow routes that don't go straight toward their target?
C) How do growth cones establish a synaptic connection with their target?
D) How do growth cones move when filopodia cannot adhere to the external substrate?

Question 41

Axon guidance allows neurons to connect to their appropriate targets. Growing neurons must find their targets, some of which are very nearby (such as in a developing embryo) and some of which are farther away. Outline the processes that allow neurons to know the "routes" to take over short and long distances.

Question 42

Consider the process described in figure 4.22. in the text Create a figure that depicts how chemotactic signaling molecules and their receptors interact and change to allow axons to first grow toward the floor plate and then away from the floor plate in the developing spinal cord.

Question 43

The ability to re-grow neurons and help them form appropriate connections would greatly benefit patients with spinal cord injuries. Predict what some of the obstacles might be in helping adult patients regain full function in the nervous system after damage to axons has occurred?

Question 44

Which statement best characterizes the contrasts between axon guidance in the developing spinal cord and retina?

A) Ephrins serve as the primary repulsive cue in both tissues.
B) Axon guidance toward the floor plate relies primarily on substrate-bound axon guidance molecules.
C) Axon guidance in the retina is very specific, whereas it is relatively indiscriminate in the spinal cord.
D) Growth toward both the floor plate and retina involve repulsion.

Question 45

Predict what would happen if a gene necessary for the expression of ephrin was mutated so that it becomes non-functional.

A) Nasal axons would grow toward the rostral and caudal tectum
B) Nasal axons would only grow toward the rostral tectum only
C) Nasal axons would grow toward the caudal tectum only
D) Nasal axonal growth would be inhibited

Question 46

Which is NOT true of dendrite development?

A) Dendrites are repulsed by other dendrites and don't usually overlap.
B) Dendrites that have not formed synapses express neurotransmitter receptors.
C) Dendrites contain filopodia all along their length.
D) Dendrites tend to develop in clumps rather than being spread out like axons.

Question 47

Which of the following needs to occur to begin the process of synapse formation?

A) Molecules such as agrin and neurexin bridge the pre- and post-synaptic cells.
B) Post-synaptic neurotransmitter receptors cluster together.
C) Structural proteins form that shape the synapse.
D) All of the above are true.

Question 48

In your research lab you observe a number of brain sections under the microscope from various phases of development in a mouse embryo. You notice that in the later sections, fewer neurons are present. What might you conclude?

A) The mouse has a disorder that affects neuronal development and would not have lived to adulthood.
B) As the cells died, they likely caused damage to adjacent cells due to release of intracellular contents.
C) The mouse is developing normally and the neuronal loss is expected.
D) The neurons likely died because they were inappropriately attacked due to the immature immune system.

Question 49

Relate the study of embryonic chickens to the discovery of trophic factors.

Question 50

Analyze figure 4.30 In the text. Which of the following is true of this figure?

A) This figure depicts a loss of sensory neurons that innervate the wing.
B) This figure depicts a loss of motor neurons that innervate the wing and leg.
C) This figure depicts trophic factors binding to their molecular targets in the spinal cord.
D) None of the above are true.

Question 51

An example of a chemical compound that can stimulate neuronal growth is ________________________.

Question 52

In the text, the author states: "It is a strange sort of economy: if demand for neurotrophic factor exceeds the supply, then the demand is trimmed. Thank goodness our own economies tend to adjust supply instead!". What does demand and supply refer to in neuronal development, and how does it relate to the presence of trophic factors?

Question 53

The phrase "pruning" is used to describe the development of the nervous system. The author contrasts this with marble sculpture. What do these analogies represent?

A) They relate to the loss of neurons early in development.
B) They relate to the loss of axons that do not receive trophic support.
C) They relate to growth cone growth and retraction during chemotaxis.
D) All of the above are true.

Question 54

You label the developing corticospinal neurons of a cat with a fluorescent compound that permits axon visualization. You see that in the spinal cord, fluorescence is found on only one side of the spinal cord. This finding suggests that the age of the animal is most likely

A) less than 25 days
B) at least 25 days
C) at least 35 days
D) at least 55 days

Question 55

Based on findings regarding retinal activity waves in utero, which of the following would NOT be expected in a developing organism?

A) neurons in the developing organism display some level of activity regardless of function
B) neurons are largely inactive until performing a task that requires them
C) if retinal activity waves were synchronized, the LGN would continue to receive input from both retinas
D) synapses in the LGN are glutamatergic

Question 56

Consider the retina, LGN, and visual cortex. Which of the following is a true statement?

A) In a normal adult, each LGN is largely responsive to visual stimuli from one eye, while visual cortex responds to visual stimuli from both eyes.
B) In a normal adult, each LGN is largely responsive to visual stimuli from both eyes, while visual cortex responds to visual stimuli from one eye.
C) In a normal adult, the LGN areas and visual cortex respond to visual stimuli from both eyes.
D) LGN and visual cortex both respond primarily to inputs from one eye.

Question 57

The time during development when the nervous system is vulnerable to a specific environmental variable is known as the ________________________.

Question 58

Why is it dangerous for a pregnant woman to take the drug Accutane? Propose a hypothesis that specifically addresses the role of retinoic acid as described in previous chapters.

Question 59

Excessive alcohol exposure is harmful at all ages, but particularly during development. How is it that alcohol produces such deleterious effect at early ages?

A) It may impair neurogenesis
B) It may impair neuronal migration
C) It may lead to abnormally high rates of neuronal death
D) all of the above

Question 60

Which areas of the brain tend to develop first?

A) rostral and dorsal
B) caudal and dorsal
C) rostral and ventral
D) caudal and ventral

Question 61

The author states: "the fact that different brain regions develop and mature at different times is an effective compromise that allows organisms to survive outside the womb right after birth yet learn what's needed to be a successful adult.". If some areas of brain development aren't complete until the teenage years or later, what do you think is driving this evolutionary compromise? In other words, what traits might be "essential" for a species that are present before the brain is fully developed?