Deck 4: Neural Differentiation

Question 1

What is each hexagonal cluster of photoreceptors in the Drosophila visual system called?

A) Compound eye
B) Morphogenetic furrow
C) Ommatidium
D) Hexatidium

Answer 1

C

Question 2

What process drives the compound eye of Drosophila to develop from a uniform disc of cells?

A) Mitotic lineage
B) Divisions from a single precursor cell
C) Mosaic specification
D) Cell-cell interactions

Answer 2

D

Question 3

Early in the developing Drosophila eye, cells next to the posterior eye disc release _______ to direct adjacent cells to differentiate into _______.

A) boss; morphogenetic furrow cells
B) sevenless; photoreceptor R8
C) hedgehog (hh); ommatidia
D) Sonic hedgehog (Shh); retinal cells

Answer 3

C

Question 4

If the hedgehog gene was nonfunctional in a developing Drosophila, what might happen to the morphogenetic furrow in eye development?

A) No morphogenetic furrow would form
B) The morphogenetic furrow would move too quickly
C) The morphogenetic furrow would move too slowly
D) The morphogenetic furrow would move across the optic disc without any cells differentiating

Question 5

What happens to the development of the Drosophila compound eye if the sevenless gene is dysfunctional?

A) The surrounding cells take over its function.
B) The fruit fly will have no eyes.
C) The fruit fly will not see UV light.
D) The fruit fly will only see UV light.

Question 6

The secreted factor _______ induces postmitotic cells to become _______.

A) BMP; astrocytes
B) Delta; astrocytes
C) BMP; neurons
D) Delta; neurons

Question 7

The cell membrane factor _______ induces postmitotic cells to become _______.

A) BMP; astrocytes
B) Delta; astrocytes
C) BMP; neurons
D) Delta; neurons

Question 8

In vertebrate development, the notochord secretes _______, which induces formation of the _______ plate.

A) BMP; roof
B) BMP; floor
C) Shh; roof
D) Shh; floor

Question 9

In vertebrate development, the overlying ectoderm secretes _______, which induces formation of the _______ plate.

A) BMP; roof
B) BMP; floor
C) Shh; roof
D) Shh; floor

Question 10

Which comes first in the process of spinal motor neuron differentiation?

A) Cells adjacent to the neural tube begin expressing Isl-2.
B) Cells at different levels of the spinal cord begin expressing particular Hox genes.
C) Cells adjacent to the neural tube begin expressing Isl-1.
D) Floor plate cells begin expressing Sonic hedgehog.

Question 11

Neural tube cells that will become motor neurons first express the gene _______, which makes a protein that turns on the expression of _______.

A) Isl-2; Isl-1
B) Isl-1; Isl-2
C) Lim-3; Isl-1
D) Lim-3; Isl-2

Question 12

What determines which subpopulation of motor neuron pools a differentiating spinal motor neuron will belong to?

A) Cells in different motor neuron pools express different levels of Isl-1 and Isl-2.
B) Cells at different levels of the spinal cord express unique combinations of Hox genes.
C) Cells at different levels of the spinal cord express varying levels of Sonic hedgehog.
D) Cells in different motor neuron pools receive different factors from the tissue they innervate.

Question 13

Generally, neural crest cells that form the sympathetic ganglia release _______, and those that form the parasympathetic nervous system release _______.

A) acetylcholine; norepinephrine
B) acetylcholine; epinephrine
C) norepinephrine; acetylcholine
D) epinephrine; acetylcholine

Question 14

If an individual develops into a chimera, it will

A) not be able to reproduce.
B) not survive.
C) contain cells that all have identical genotypes.
D) contain cells that do not all have identical genotypes.

Question 15

If embryonic neural crest cells that normally become parasympathetic neurons are transplanted into the region that normally develops into sympathetic neurons, and those transplanted cells take on a sympathetic fate, what does this suggest about how autonomic neural crest cells are directed to become sympathetic or parasympathetic?

A) Neural crest cell fates are determined before they begin migrating away from the neural tube.
B) Neural crest cells are differentiated when they leave the neural tube.
C) Neural crest cell fates are not determined by where they originally arise in the spinal cord.
D) Neural crest cells that do not express the appropriate phenotype for their location die.

Question 16

An injury that causes Schwann cells to become melanocytes is an example of

A) differentiation.
B) dedifferentiation.
C) mutations.
D) migration.

Question 17

Sympathetic and parasympathetic neurons typically have _______ effects on their target organs.

A) synergistic
B) opposing
C) synchronous
D) asynchronous

Question 18

Early in development, postganglionic neurons in the autonomic nervous system release

A) only acetylcholine.
B) only norepinephrine.
C) both acetylcholine and norepinephrine.
D) no neurotransmitters.

Question 19

Sweat glands are innervated by _______ nervous system neurons that release _______.

A) sympathetic; norepinephrine
B) parasympathetic; norepinephrine
C) sympathetic; acetylcholine
D) parasympathetic; acetylcholine

Question 20

In cortical cell migration, the last layer that is populated is layer

A) I.
B) II.
C) IV.
D) VI.

Question 21

Which mechanism causes a postmitotic cortical neuron to settle in a particular layer depending on when it was born?

A) The neuron itself keeps track of its birthdate and targets the layer appropriate to its birthdate.
B) Cells in the destination cortical layer inform the migrating neuron to stop.
C) The neuron migrates without instruction and stops when there is an open space in the cortex.
D) The neuron receives destination information from the ventricular zone before it migrates.

Question 22

When fetal ferret ventricular zone cells are transplanted into an older ferret, after undergoing their final S phase, they migrate to cortical layer

A) I.
B) II.
C) VI.
D) V.

Question 23

What is the last region to mature in human brain development?

A) Prefrontal cortex
B) Motor cortex
C) Olfactory epithelium
D) Sensory cortex

Question 24

_______ is the phenomenon whereby a descendant species stops development at what was a juvenile stage in its ancestor.

A) Morphogenesis
B) Chimerism
C) Evolution
D) Neoteny

Question 25

What is responsible for the expanded neocortex in humans?

A) The outer layers grow more extensively than the earlier, inner layers.
B) The inner layers grow more extensively than the later, outer layers.
C) All cortical layers are expanded.
D) The outer layers develop before the inner layers.

Question 26

In the developing Drosophila optic disc, in what anatomical direction does the morphogenetic furrow move, and what are the characteristics of the cells in front of and behind it? In what way does the morphogenetic furrow organize the development of the compound eye, and what does this suggest about how ommatidia arise from the optic disc?

Question 27

A stochastic process is one that is influenced by a collection of random variables that can be studied statistically but cannot be predicted precisely. Using what you have learned about how postmitotic cells differentiate into neurons or glia, in what way is cellular differentiation a stochastic process?

Question 28

Refer to the figure.
In the sections of developing neural tubes shown, which fate will each of the developing motor neurons (A: purple, B: red, C: green, and D: blue) take on with respect to which tissues they will innervate?

Question 29

In what way are the neural crest cells that become the sympathetic neurons anatomically segregated from those that become the parasympathetic neurons?

Question 30

How does the bacterium responsible for Hansen's disease lead to the dedifferentiation of Schwann cells, and how does this cause the symptoms of the disease?

Question 31

If sweat gland tissue from a rat is transplanted into to the back, which neurotransmitter will the sympathetic fibers in the back that subsequently innervate the newly transplanted sweat gland tissue release? What does this tell us about the differentiation of sympathetic fibers, particularly those that innervate sweat glands?

Question 32

In cortical neuron migration, ventricular cells that have not undergone their final division can take on the fate appropriate to the age of a host when transplanted into another individual's ventricular zone, but ventricular cells that have undergone their last division in the donor will always settle in the cortical layer appropriate to the donor's stage of development at the time of transplant, regardless of the age of the host. How does this relate to the overall concept of age and self-regulation in embryonic development?

Question 33

What are the three broad types of pathways in which differentiating cells are influenced by other cells? What is the final common mechanism by which all of these pathways influence cell fate?

Question 34

What is a possible reason why human brain development continues outside the womb?

Question 35

Refer to the figure.
Based on the data shown, which compares brain weight during development in humans and chimpanzees, what can you conclude about the similarities and differences between human and chimpanzee brain development outside the womb? What brain difference in adulthood results from these developmental differences?