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Entomology, Spring 2006
Study questions for Neurobiology, Glands, Sensory Systems and Flight
1.
Although invertebrate neurons function in basically the same way as vertebrate neurons, there is
one major difference related to glial cells.
a.
What is this difference?
b.
What particular aspect of neural functioning is less efficient for the invertebrates as a
result?
c.
Do the invertebrates compensate for this in some way, and if so, how?
2.
What are the components of the central nervous system in an insect?
3.
In an insect, is the brain ventral or dorsal? What about the nerve cord? Is there one nerve cord or
two?
4.
Name the three pairs of lobes in the insect brain, and describe the major functions of each.
a.
NOTE: You do not need to memorize all the specific parts of the protocerebrum, but you
should be able to list the variety of functions carried out by the protocerebrum.
5.
Name the key functions of the Subesophageal ganglion. Where is this ganglion located?
6.
Compare the organization of the nerve cords and ganglia between annelids and insects. What is
the general evolutionary trend that occurs for insect ganglia? What are the major functions of the
ganglia (i.e. what type of information do they receive, and what do they control)? Is there a strict
1:1 correspondence between the location of a ganglion and the structures it controls?
7.
What are the key functions of the insect’s visceral nervous system? Know which parts of the
visceral nervous system receive input/control which particular structures.
8.
What are the key functions of the insect’s peripheral nervous system (i.e. where does sensory input
come from, and where does motor output go)? How is the peripheral nervous system related to
the central nervous system?
9.
What are exocrine glands, and with what general type of tissue are they associated?
10.
List several functions of exocrine glands, and be able to provide specific examples of each.
11.
How does an endocrine gland differ from an exocrine gland? What are the major types of
processes that the endocrine system controls in insects?
12.
Name the two major pairs of endocrine glands in adult insects. In addition, name several other
body structures that may act as endocrine glands in adult insects.
13.
Name an endocrine organ found only in immature insects.
14.
What is the function of the neuroendocrine system? How do neurosecretory cells differ from
ordinary neurons?
15.
In a step-by-step way, describe how the protocerebrum could ultimately control the release of
ecdysone from the thoracic glands, indicating all organs, cell types and specific secretions that are
involved.
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16.
What is the key function of any sensory structure?
17.
Label the following parts of the insect eye in both an apposition and superposition eye, and know
the function of each of these parts:
a.
ommatidium
b.
corneal lens
c.
crystalline cone
d.
corneal pigment cell
e.
rhabdom
f.
retinular (receptor) cell
18.
What are corneal nipples? Describe a couple of possible functions for them.
19.
What are interommatidial hairs? What is their function?
20.
Be able to recognize the ommatidial structure of a primarily diurnal insect vs. the ommatidial
structure of a primarily nocturnal insect.
21.
How does the nocturnal eye adjust for higher light vs. lower light conditions? What aspect of
vision might be impaired when its eye is configured for “night vision” and why?
22.
What is/are the key adaptive advantages of a compound eye over a "simple" eye (such as what
we've got?)
23.
What is/are the key limitations of a compound eye?
24.
What factors affect the acuity of an insect eye, and in which direction (for example, does a bigger
or a smaller compound eye have greater acuity?) You should be able to name three factors.
25.
Briefly describe the experiments done by Karl von Frisch to show that bees have color vision.
26.
Describe two major functions of ultraviolet vision for insects with this ability.
27.
Briefly describe the experiments with bee flight in the wind tunnel with a horizontally-striped,
moving floor. What did these experiments show?
28.
What's the deal with tsetse fly vision and zebra stripes (two hypotheses?)
29.
What are lateral ocelli, and which insects/life stages have them?
30.
What are dorsal ocelli, and with what aspect of insect life are they correlated?
31.
Which three cell types form a trichoid-type sensillum, and what (basically) is the function of each
of these cell types? Where are these type of sensillae found?
32.
Some trichoid-type sensilla have >1 receptor cell. What might this indicate?
33.
Describe three different mechanoreceptive functions of trichoid-type sensilla.
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34.
How do campaniform sensillae differ from most other trichoid-type sensillae? What types of
stimuli do they detect?
35.
Describe the basic structural differences between chemosensitive sensillae that respond to odors
form far away (i.e. “olfactory” sensillae) vs. those that respond only when they directly contact the
substance (i.e. “contact sensillae”)?
36.
Describe several places on the insect body where chemosensory sensillae are located.
37.
How do the tasting abilities of honeybees compare to humans?
38.
Describe chordotonal sensillae, using the subgenual organ of an ant as a model. Be sure to
indicate
a.
The position of the organ with respect to the integument.
b.
The appearance/location of the bipolar neurons
c.
Any other specialized cells
d.
What is necessary to stimulate these organs
39.
To what types of stimuli are chordotonal sensillae sensitive?
40.
Under what broader category of sensation does hearing belong?
41.
What is sound, and what are the two major ways it can be perceived by insects?
42.
Name several orders of insects that both send and receive sound.
43.
What are the major functions of auditory communication in insects?
44.
From what type of sensillae are insect ears derived?
45.
Be able to label a cross section of the katydid (longhorn grasshopper) tympanal organ, and
describe the major function of each of these parts:
a.
tibial slit
b.
tympanal cavities
c.
tracheal sac
d.
tympanum
e.
chordotonal sensillae
46.
Describe the pathway that sound takes through the katydid ear.
47.
Where does transduction actually take place in the katydid ear?
48.
Which structures in the katydid ear are most responsible for responding differently to different
frequencies?
49.
What is meant by a “bat detector” neuron in a cricket, and where is this presumed “bat detector”
neuron located? To what frequencies does it best respond?
50.
Under what types of stimulation does this “bat detector” neuron appear to respond rather quickly?
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51.
Under what types of stimulation does this “bat detector” neuron appear to be inhibited despite the
presence of a 30 kHz (bat frequency) stimulus? How could this possibly be adaptive from an
evolutionary standpoint?
52.
Is the brain required for the “bat detection” system in crickets to elicit an escape response?
53.
Describe three benefits of flight in insects.
54.
What is the fastest published record of insect flight, and in which insect was this observed?
55.
From what specific structures of the thorax are the wings formed?
56.
Where are basal sclerites located, and what is their function?
57.
Where are the direct flight muscles attached (between which two types of structures?) What are
the major functions of the direct flight muscles?
58.
Describe the structure of the thorax, indicating the position of the three different types of plates.
59.
What is meant by “resonating muscle fibers” and what is their importance to insect flight?
60.
What are the two types of indirect flight muscles, and where are they located/attached? What is
the major function of each of these two different types of indirect flight muscles during the process
of flight? Describe the shape change that each type of muscle causes to the thorax.
61.
Describe how the upstroke and downstroke are generated. Include the role of the different muscle
types, as applicable, as well as the function of the thorax itself (HINT: Understand the "click
mechanism" at the level explained in the lecture notes.)
62.
Why is the horizontal wing position "unstable", while the fully upward and downward positions
are both stable?
63.
Do the wings go straight up and down during flight? If not, in what positions do they go?
64.
What enables the wings to twist, rather than bend, on the upstroke (refer to Fig. 11 in the handout,
which shows this)? What is the advantage of this twisting?
65.
Briefly describe the factors which enable an insect to turn in flight.
66.
Why is 4-winged flight potentially inefficient? What mechanisms have evolved to deal with this
potential problem? List the alternate mechanisms, and provide specific examples.
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