Study Questions for Biology 204L
1.
2.
3.
4.
Define homeostasis.
What is meant by homeostatic parameters? List a few examples.
What is an enzyme? Define catalyst (or catalysis).
Present a model of a basic enzyme-catalyzed reaction and use it to discuss how enzymes ‘work’.
Be sure to include the following terms/concepts in your discussion:
 Enzyme-substrate complex
 Lock-&-key model
 Enzyme-substrate affinity
 Conformation change
5. How does enzyme-substrate affinity affect enzyme-catalyzed reaction rates?
6. Discuss stabilization of enzyme tertiary and quaternary conformation. In particular, explain why
enzymes depend on weak electrostatic interactions for their structural stability.
7. What did I mean when I said that enzymes are “on the horns of a dilemma”? How do enzymes
resolve that dilemma?
8. What do you believe is the take-home message of Figure 41.1 in your text?
9. What do enzymologists mean by the term modulation?
10. In general terms, how do modulators work? How do positive modulators and negative modulators
differ?
11. What is the Law of Mass Action, and how is it relevant to enzyme-catalyzed reactions?
12. What is the importance of enzyme modulation for cells?
13. What is the relevance of enzyme function to homeostasis?
***End 1st Lecture***
14. Define adaptive significance.
15. Are organisms in complete equilibrium with their environment? Explain.
16. How do gradients and exchanges relate to homeostasis? Which term represents the ‘driving force’ for
the other?
17. The form of energy that ‘moves’ in response to a temperature gradient is called ____________?
18. What is meant by the term flux?
Q
 k Tobj  Tenv  . Which term represents the driving
19. Explain in words the following equation:
t
force in the equation?
20. List some factors that determine the value of k in the equation in the preceding equation.
21. Suppose you placed a warm object in a cold environment. Draw the graph representing how the
object’s temperature would change with time. (be sure to label the axes!). Write the equation that
describes the graph.
22. Suppose you placed a cold object in a warm environment. Draw the graph representing how the
object’s temperature would change with time.
23. Draw a graph that shows the difference between a regulator and a conformer for some homeostatic
parameter.
24. Describe an experiment that could be used to demonstrate the difference between a poikilotherm and a
homeotherm. Which are you?
25. Discuss the example we used in class to illustrate the cost(s) of being an osmoconformer.
26. Is being a conformer always a bad thing?
27. Compare and contrast endothermy and ectothermy. Are these strategies employed by
thermoconformers, or thermoregulators? Which are you?
***End 2nd Lecture***
28. Defend or refute the following statement: data from Baltic Sea starfish leads to the prediction that all
animals should osmoregulate.
 If you defend the statement, explain why the starfish doesn’t osmoregulate.
 If you refute the statement, explain why the starfish doesn’t osmoregulate.
29. In the context of ecology and evolution, what is meant by the term cost? Are costs a common feature
of most adaptations?
30. Why did I say that true poikilotherms are at the mercy of their thermal environment?
31. List and discuss in as much detail as you can the three costs of thermoconformity I presented in
lecture.
32. Graph the following data and calculate the Q10 for each reaction:
Temperature Reaction Temperature Reaction
( oC )
#1
( oC )
#2
0
1
5
1
10
3.5
11
1.5
20
12.25
25
4
30
42.9
35
8
40
150.1
40
11.3
50
525.2
55
32
33. TRUE or FALSE: the Q10 phenomenon is only observed in the case of enzyme catalyzed reactions.
 If you answered TRUE, explain why other processes don’t exhibit a Q10 effect.
 If you answered FALSE, give me some examples of other processes that illustrate a Q10
effect.
34. Give examples of the cost of thermoregulation (i) for ectotherms, and (ii) for endotherms.
35. Do most organisms thermoregulate, if given the opportunity? If so, what does that imply? If not,
what does that imply? (hint: think costs and benefits of regulation versus conformity)
***End 3rd Lecture***
36. Draw a graph that illustrates the differences between the daily patterns of body temperature in an
ectotherm and an endotherm. What is meant by the term preferred body temperature? How do
ectotherms achieve their preferred body temperature?
37. With respect to time courses of adaptation, what ***sets the limit*** for the immediate time scale?
38. Over immediate time scales, cells must adapt to temperature change using
__________________________________________________________.
39. Describe the experiment we used to illustrate an ectotherm’s response to temperature change over
immediate time scales. Draw the graph of the data we obtained from that experiment. BE SURE
TO LABEL THE AXES OF THE GRAPH. Also, be sure to put your experiment in a proper
environmental context; i.e., give a description of the environmental conditions experienced by the
periwinkle.
40. What is meant by the term metabolic rate? By VO2 ? What does metabolic rate reflect? What can we
learn about an organism by measuring its metabolic rate?
41. ***What is the term we apply to the response exhibited by the periwinkle to changes in temperature
over immediate time scales?***
42. How did we a Q10 model to help us interpret the data we obtained from our periwinkle?
43. What role did enzyme-substrate affinities play in the ability of the periwinkle to survive drastic
changes in temperature?
44. With respect to thermobiology, in ectotherms the priority is _____________________________,
while in endotherms, the priority is
____________________________________________________.
45. Describe the experiment we used to illustrate an endotherm’s (i.e., your) response to temperature
change over immediate time scales. Draw the graph of the data we obtained from that experiment.
BE SURE TO LABEL THE AXES OF THE GRAPH. What is the name given to the graph?
46. What is meant by Upper Critical Temperature (UCT) and Lower Critical Temperature (LCT)? By the
term Thermal Neutral Zone? What sets the LCT
47. What is basal metabolic rate, and what does it reflect?
48. Use a cartoon representation of an endotherm to help you discuss how an endotherm can maintain its
body temperature constant in the TNZ without changing its metabolic heat production.
49. What is piloerection, and what is its role in thermoregulation?
***End 4th Lecture***
50. What is the only heat-dissipation option available to endotherms when exposed to high ambient
temperatures? Why does it work to dissipate heat?
51. How do birds and mammals facilitate evaporative cooling? Is their a drawback to the mechanism(s)
they employ?
52. When we speak of physiological adaptation over intermediate time scales, what sets the lower limit
for the time scale?
53. Draw the graph that illustrates temperature acclimation in a British Isles periwinkle. What is the
mechanism that allows the periwinkle to acclimate?
54. Draw the graph that illustrates how endotherms acclimate to temperature change over seasonal time
scales. What is the name of the hormone that mediates this acclimation? Where is the hormone
produced, and how is its production regulated? What is its mechanism of action, and what is the
consequence of its action?
***End 5th Lecture***
55. Besides increasing metabolic heat production, what other contribution to thermoregulation does
thyroxine make?
56. Using an appropriate graph, explain the effect of thyroxine on Lower Critical Temperature.
57. The slope of the Curve of Thermogenesis below LCT is a measure of what? What is the term that we
apply to the slope? How does the equation presented in Question 19 relate to the Curve of
Thermogenesis?
58. What is meant by the term ontogenetic?
59. Describe acclimation of sweating in humans over short-term (days) and ontogenetic time scales.
60. Describe a couple examples of evolutionary adaptation in ectotherm thermobiology.
61. What is meant by the term phenotypic plasticity? How is it adaptive? Does it impose any
ecological/evolutionary costs on organisms? Cite an example to support your point.
62. How do ectotherms benefit if they’re able to maintain their body temperature at Tpref? Can you offer
an explanation for ***how this benefit occurs***?
63. Using examples discussed in lecture, illustrate and discuss evolutionary adaptation of the Curve of
Thermogenesis. What phenotypic characteristics account for the observed differences in the curves
you drew?
64. Describe the physiological response of a wolf whose foot is exposed to severe cold stress. Compare
that with the response we’d expect to observe in you, and in an Inuit.
65. Compare and contrast your cold-stress response with that of an Australian Aborigine. What seemed
to be the priority for your response? For the Aborigine’s?
66. Using the examples of human evolutionary adaptation to cold environments, discuss the role played
by the environment in determining the ‘direction’ taken by the adaptive process.
***End 6th Lecture***
67. How do we define “potential” in the electrical sense?
68. How do we define “current” in the electrical sense?
69. What is responsible for current in a copper wire? What is responsible for current in most biological
systems?
70. What do we mean by the term membrane potential?
71. Potentials – of batteries, electrical outlets, or membranes – are measured in units of
____________________?
72. In biological systems, potentials results from _____________________________.
73. What is meant by the term conductance?
74. Use your answers to the preceding questions to discuss the ionic basis for the membrane potential. Be
sure that your discussion includes the following:
 Role of K+, Na+, non-diffusible anions (A-).
 The importance of membrane conductance for K+, Na+, and A-.
 The importance of rates of Na+ and K+ flux through the membrane.
75. Under most circumstances, the primary determinant of the magnitude of the resting membrane
potential is _________________________________________. Why is this?
76. The effect of Na+ on resting membrane potential is to ______________________.
77. Use a graph to illustrate the following:
 Depolarization
 Hyperpolarization
 Repolarization
78. Thinking in terms of ion fluxes, concentration gradients, and membrane conductances, give me as
many ways as you can think of that depolarization could be brought about. Now, do the same for
hyperpolarization.
79. Draw a graph of an action potential (be sure to label the axes), and give a verbal description of what
the graph represents. Indicate the following on your graph:
 Resting membrane potential (Vm).
 Threshold (is it a thing, a place, a time, or a potential?).
 The spike.
 Afterpotential.
 Occurrence of gNa+, gK+,  gNa+, and  gK+.
th
***End 7 Lecture***
80. Using the graph you constructed in the preceding question, discuss the ionic basis for an action
potential.
81. Using a suitable cartoon diagram such as the one I presented in lecture, discuss voltage-gated sodium
channels and their role in action potentials. Why do we say that they’re “voltage-gated”? Now, do
the same for voltage-gated potassium channels.
82. According to your textbook, how do action potentials progress from place-to-place along an axon?
83. What is meant by the term refractory period, and why is it important in neuron function?
84. What is the mechanism of action of tetrodotoxin (TTX) and novocaine? What effects do they cause?
85. Diagram and label an acetylcholine-mediated synapse and use that diagram to help you list & discuss
the process of synaptic transmission of action potentials from one cell to another. Be sure to
include the following in your discussion:
 Ca++.
 SNARE complex.
 Degrading enzyme.
 Reuptake transporter protein.
 Summation
86. How do inhibitory synapses differ from excitatory synapses? Are inhibitory synapses important in
functioning of your nervous system? Justify your answer with some evidence.
***End 8th Lecture***
87. Draw a flow chart that depicts signal transduction by a receptor, and use this to describe/discuss the
process. Be sure to include the following in your discussion:
 Membrane conductance.
 Receptor potential.
 Tonic versus phasic receptors
88. What do we mean when we say that receptors are selective transducers?
89. Draw a Pacinian corpuscle and describe how it transduces stimulus energy. What type of receptor is
it?
90. What is a drawback or limitation to the way Pacinian corpuscles function, and how does the brain
‘work around’ this limitation?
91. What are some important ‘uses’ of Pacinian corpuscles?
92. Diagram and label a typical hair cell receptor and a present a graph of its electrical response to
stimulation.
93. How has evolution adapted hair cell receptor function in fish?
***End 9th Lecture***
94. What is meant by the term stimulus filtering? Describe the example I presented in lecture.
95. In the following image, indicate the location of the following structures, and give the function of those
indicated by an asterisk:
 cerebrum
 cerebellum*
 brainstem*
 medulla oblongate*
 frontal cortex*
 motor cortex*
 somatosensory cortex*
 visual cortex*
 basal ganglia*
 pons*
96. What is meant by the term object agnosia? By the term prosopagnosia? What do they result from?
97. What is implied by the fact that some people with object agnosia only have difficulty perceiving
stationary objects, while others don’t perceive moving objects well, if at all?
98. In the following image,
 a person suffering from object agnosia would perceive the man’s face, but would not realize
that it was actually composed of fruits and vegetables,
 a prosopagnosia sufferer would see the individual fruits and vegetables, except where they were
grouped to produce the man’s face.
Isn’t that fascinating?
99. Diagram the central nervous system as it relates to control of the body’s muscles, and use it to discuss
the basics of how your brain accomplishes purposeful movements. Be sure that you include the
following terms in your diagram & discussion:
 Frontal cortex
 Motor cortex
 Betz cells
 Somatosensory cortex
 Proprioceptors
 Motor neurons
 Cerebellum
100. Describe and discuss the feedback loop that the cerebellum employs during its control of muscle
activity.
***End 10th Lecture***
101. Why can’t the cerebellum rely on its feedback loop when it’s controlling very rapid movements?
How does the cerebellum solve the problem of controlling rapid movements?
102. What is the role played by the basal ganglia in control of the muscles of the body, and why is it
important?
103. What is Parkinsonism? What does it result from? What are its principal signs and symptoms? Does
it illustrate the importance of inhibitory function in the nervous system?
104. What are three consequences of cerebellar trauma, and what do they result from?
105. Use the following diagram to help you describe how the knee jerk reflex occurs.
106. Use the following diagram to describe how a withdrawal reflex would work if, as your favorite
experimental organism put his/her/its foot down to stand up from a seated position, he/she/it stepped
on a thumb tack. Assume that the withdrawal reflex would kick (extend) the leg upward.
107. What is the crossed extensor reflex, how is it brought about, and why is it necessary?
108. A key aspect of most nervous systems’ function is a hierarchy of control over bodily functions. How
is this illustrated in my lectures on control of the musculoskeletal system? Can you think of any
reason(s) that hierarchical levels of control should be so frequently encountered in nervous systems?