Exam 2 - Zoology 250
Version A
Instructor: John Godwin, Fall 2002
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This exam has 8 pages, Please check that your copy is complete.
Terminology/short answer - These questions require terms or brief answers. (15 questions, 1
pt. each except where noted, 30 pts total)
1. Assume you have a chamber which you fill half with water and half with air. Into the air portion,
you introduce a mixture of 50% O2 and 50% CO2. After the mixture equilibrates with the water,
you measure the total amount of O2 and CO2 in the water (think of CO2 and the forms it is
converted to when considering how much CO2 the water contains; 3 pts)
• Which gas do you find more of in the water?
• Why specifically do you find more of one or the other?(refer to the physical properties of the gas)
• What is the main chemical form the CO2 is converted to in the water?
You would find more CO2 than O2
- CO2 is much more soluble in water than O2 is
- The main chemical form for CO2 is bicarbonate ion, HCO3- (half credit for carbonic acid,
H2CO3)
2. Now, imagine you change the mixture to 90% O2 and 10% CO2, let it equilibrate with the water
again, and now measure the pH. How will the pH now compare with the pH that would result
from equilibration with the 50% O2, 50% CO2 air mixture of the last question?
The pH would be higher
3. Pick either a fish gill or mammalian lung and briefly note two ways in which its structure and/or
function are specialized to increase the efficiency of gas exchange. Feel free to use simple
diagrams in your answer here if you find it helpful. Second, give two physical reasons that
respiration in water is more challenging than respiration in air (4 pts)
Fish gill possibles: thin epithelium (reduces distance), large gill area (increases surface
area), and maintenance of gradients through countercurrent exchange
Mammal lung: thin epithelium, large surface area due to alveoli, and maintenance of
gradients by breathing (respiration)
Reasons why respiration in water is more difficult than air: Water is dense (difficult to
move), O2 diffuses slowly in water, and oxygen is not very soluble in water (leading to low
levels of it being available)
4. What structure in fishes gave rise to the lungs we see in terrestrial vertebrates?
The swim bladder
5. What are the respiratory structures of insects termed? Does this system depend on the circulatory
system to deliver and remove respiratory gases? (2 pts)
Tracheal systems. No, they do not depend on the circulatory system
6. Most oxygen in the blood of a vertebrate is transported in what way?
- bound to hemoglobin
7. The extensive bony shelves found in the nasal passages of the vast majority of endotherms are
termed ________.
- respiratory turbinates (half credit for just turbinates)
8. A danger of treatment with antibiotics is the development of opportunistic infections. Why do
these opportunistic infections typically not develop in the absence of antibiotic treatment? (i.e.,
what general defense does this illustrate?)
Ecological competition with the normal bacterial flora prevents pathogens from using those
nutrients
9. Does fever represent only a symptom of illness or a defense against it? (1 pt) Briefly describe
one of the experiments we discussed in class that supports your answer (2 pts, 3 pts total).
Fever is a defense. We talked about two separate experiments that would be suitable here.
In one experiment, rats with an infection and fever have their environment cooled. Their
body temperature remains elevated above normal despite this cooling, indicating they are
actively regulating their temperature at an elevated level.
A second experiment we discussed used desert iguanas. This is a nice approach because
you can essentially ask these ectotherms how warm they want to be when they have an
infection vs. not and they will tell you by choosing to be in a warmer or cooler environment.
When infected, desert iguanas elevate their temperature behaviorally this way and do better
when they are allowed to do this (rather than remaining cool)
10. List the four key features of the immune system and very briefly describe what property each of
these key features refers to. (4 pts) Which of these four key features does vaccination take
advantage of? (1 pt.)
Specificity: The immune system can generate antibodies that are very specific to features
of particular pathogens or toxins
Diversity: The immune system can generate an enormous diversity of different antibodies.
Memory: The immune system is able to respond more quickly on its second exposure to a
particular antigen (usually associated with a pathogen)
Self/Non-self recognition: The immune system has the ability to differentiate tissues of the
body from foreign cells (failures here underlie autoimmune disorders)
Vaccination takes advantage of the memory feature of the immune system (i.e., giving it a
memory with inactivated pathogens or parts of these so that the response to the
real thing will be more rapid and vigorous).
11. HIV cripples the immune system. What specific cell type is it particularly damaging to and why
is this so crippling to overall immune function? (2 pts)
HIV is particularly damaging to helper T cells (a.k.a. TH cells). These cells play a crucial role
in stimulating other components of the immune response (by releasing cytokines) and
damaging them therefore greatly impairs the immune response.
12. On the axes below, show the general relationship you would expect to find between
environmental temperature and core body temperature in an ectotherm using a solid line and an
endotherm using a dashed line. (2 pts)
Body
Temperature
Environmental Temperature
13. What are the two basic osmoregulatory strategies animals show?
This is a poorly worded question here, so we accepted a broad array of answers
First approach: two approaches to a osmotically variable (or just different) environment
are being an osmoconformer or an osmoregulator
Second approach: Other strategies that save waterare also acceptable here like a
concentrated urine, impermeable skin, resorbing ions from water in
freshwater, excreting ions into the water in marine fish, excreting ions via a
salt or rectal gland
14. Why are bird droppings difficult to get off your windshield? Put another way, what is their main
nitrogenous waste product and what key chemical feature of this compound does this windshield
example illustrate? (2 pts)
The main nitrogenous waste product of birds is uric acid. It is nearly insoluble in water
(meaning that it doesn't cost much in water to get rid of nitrogenous wastes)
15. How in general terms do mammals conserve water when eliminating nitrogenous wastes relative
to a lizard or bird? (i.e., why do they lose less water for a given amount of nitrogenous waste
elimination) What is the most important specialized structural feature of their nephrons for
achieving this conservation of water? (2 pts)
Mammals are able to produce a concentrated urine (concentrated relative to the blood).
The most important part of their nephrons for this is the Loop of Henle.
Multiple Choice: Use the scantron sheet for these questions ( 1 pt each, 22 pts total)
1. I am writing version ___ of this exam (No credit for this one, but it makes sure we know which
version you wrote)
a) A
b) B
2. Acetazolamide is a drug that acts as an inhibitor of the enzyme carbonic anhydrase and is
prescribed to treat glaucoma patients. Being an inhibitor of carbonic anhydrase, what side effects
would you expect this drug to have on the ability of the blood to transport CO2? (think about
transporting CO2 in the different forms it can be converted to in the blood here)
a) the amount of CO2 that could be transported would be increased.
b) the amount of CO2 that could be transported would be decreased.
c) the amount of CO2 that could be transported would be unchanged.
3. Imagine you are performing an experiment to study exchange between the parabronchial lung and
circulatory system in a bird. To do this, you introduce an inert soluble gas to a posterior air sac so
that it enters the back of the lung at high concentration. Which of the diagrams below correctly
illustrates the pattern of concentration change in your gas along the length of the bird's lung in the
air passing through the lung and the blood circulating through the lung? (on the diagrams, dashed
lines show gas concentrations in the blood while solid lines show concentrations of the gas in the
air passing through the lung; pick the letter of the appropriate diagram for your scantron sheet).
B
A
C
D
Gas
Concentration
Back
Front
Relative position in lung
4. The type of exchange found in the parabronchial lung asked about in the last question is termed:
a) countercurrent exchange
b) cocurrent exchange
c) recurrent exchange
d) paracurrent exchange
e) osmosis
5. The 'Bohr shift' refers to the change in hemoglobin affinity for oxygen with a change in blood pH.
Specifically, the affinity of hemoglobin for oxygen ________ with a lowering of pH and this
change ________ release of oxygen to the tissues.
a) increases, increases
b) increases, decreases
c) decreases, decreases
d) decreases, increases
6. If you mixed adult and fetal hemoglobin in equal amounts in solution and introduced an amount
of oxygen that would not saturate all the hemoglobin molecules (i.e., less than 100% O2
saturation), you would expect to find _______ oxygen bound to the fetal hemoglobin.
a) more
b) less
c) about the same amount of
7. Our breathing rate is regulated primarily in response to the concentration of which of the
following:
a) O2
b) CO2
c) carotid bodies
d) H+
e) Ca2+
8. The affinity of fetal hemoglobin for oxygen is _______ than the adult form in humans, _______
the transfer of oxygen from maternal to fetal circulations.
a) higher, decreasing
b) higher, increasing
c) lower, decreasing
d) lower, increasing
e) not different, not affecting
9. The circulating form of the cells that give rise to macrophages (as in the inflammation reaction):
a) Natural killer cells
b) Eosinophils
c) Neutrophils
d) T cells
e) Monocytes
10. When the body encounters an antigen:
a) all B cells respond by adapting the specificity of the antibodies they produce
b) all B cells respond by producing more of the antibody that will bind that particular antigen
c) all B cells proliferate, increasing the body's general defense against infection
d) some B cells that happen to produce the appropriate antibody proliferate
e) some B cells adjust the type of antibody they produce and then proliferate
11. The process by which the body mounts an effective antibody response to a new antigen is termed:
a) natural selection
b) clonal selection
c) inflammation
d) humoral selection
e) cell mediated selection
12. HIV gains entrance to its immune system host cells by binding two specific proteins. These are:
a) CD8 and CD4
b)
c)
d)
e)
cadherin and CD4
cytokine and CD8
reverse transcriptase and CD4
CD4 and CCR5 receptor
13. B cells and T cells arise from the same pleuripotent stem cell type initially
a) This statement is true
b) This statement is false
14. The cells of our body are equipped with 'dog tags' to identify them as belonging to the body.
These 'dog tags' are the _____ proteins.
a) complement
b) magainins
c) MHC
d) CD8
e) hemocyanin
15. The offspring of a number of animals receive protection from infection from antibodies produced
by their mothers and transferred to them. This is an example of:
a) active immunity
b) passive immunity
c) maternal immunity
d) fetal immunity
e) representational immunity
16. A fish in freshwater like a smallmouth bass or goldfish faces osmoregulatory problems,
specifically they tend to _______ water and ________ ions.
a) lose, lose
b) lose, gain
c) gain, gain
d) gain, lose
e) freshwater fish are perfectly adapted and don't either lose or gain water and ions to/from their
environment.
17. Most sharks are marine and have high urea levels that increase blood osmolarity to approximately
1000 milliosmoles. These high urea levels are an adaptation that:
a) reduces the gain of water from the shark's environment
b) reduces the loss of water to the shark's environment
c) reduces the gain of ions from the shark's environment
d) reduces the loss of ions to the shark's environment
18. African lungfish have an unusual life style. For part of the year, they live in shallow freshwater
lakes immersed in water during the wet season. These lakes disappear during the dry season
though and the fish go into 'estivation', a state in which they become inactive in a cocoon of sorts
in the dry lake bed. Based on what you know about nitrogenous waste usage in relation to
environment, you would predict that they would use _____ during the wet season and ______
during the dry season.
a) ammonia, ammonia
b) ammonia, creatine phosphate
c) urea, ammonia
d) urea, urea
e) ammonia, urea
19. The structures responsible for excretion of nitrogenous wastes in insects are termed:
a) Haversian tubules
b) Ampullae of Lorenzini
c) Malpighian tubules
d) protonephridia
e) glomeruli
20. In the part of the mammalian nephron that descends into and out of the medulla of the kidney,
both water and sodium leave the tubule. Where does each of these processes take place?
a) sodium leaves the tubule primarily in the ascending portion while water leaves the
tubule primarily in the descending portion.
b) sodium leaves the tubule primarily in the descending portion while water leaves the tubule
primarily in the ascending portion.
c) both water and sodium leave the tubule primarily in the descending portion
d) both water and sodium leave the tubule primarily in the ascending portion
21. If you were to block active transport of Na+ from nephrons in the mammalian kidney, you would
expect that the osmolarity of the urine would _______.
a) increase
b) decrease
c) not change
22. You would expect an ectotherm to have insulation to prevent heat transfer across the body
surface.
a) This statement is true
b) This statement is false.
Bonus: Tunas have larger relative gill areas than an inactive fish like a toadfish. What is the
advantage of a larger gill area? What is the major disadvantage of having a large gill area in the
marine environment? (2 pts)
Advantage: A large gill area is good for gas exhange since this provides a large surface
area over which gas exchange can occur.
Disadvantage: The primary problem for marine fish arising at the gills is the loss of water by
osmosis and gain of ions. Decreasing this gill area in a less active fish helps reduce the
magnitude of these problems.