Biology 451 – Comparative Physiology – Exam 1

Pledge: In recognition of and in the spirit of the honor code, I certify that I have neither given nor received aid on

this examination.

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(Full Name, printed) ________________________________Student I.D. Number ____________________

Water vapor over a free water surface: 46.9 mmHg @ 37C; 31.7 mmHg @ 30 C; 17.5 mmHg @ 20 C;

12.8 mmHg @ 15 C; 9.2 mmHg @ 10°C

Solubility Coefficients @ 20C:  = 31 ml O2/l H2O;  = 878 ml CO2/l H2O;  = 15 ml N2/l H2O

Solubility Coefficients @ 15C:  = 34.1 ml O2/l H2O;  = 1019.0 ml CO2/l H2O;  = 16.9 ml N2/l H2O

MW of O2 = 32, MW of CO2= 44, MW of N2 = 28

For complete credit please show all calculations and units for problems 1-4 below. Write the correct answer

in the blank on the left side of the page for questions 5-7 (2 points per question)

Following the disastrous earthquake in Haiti, you are part of a team that has been contracted to conduct a survey of

the fauna and to document its recovery.

1) You land in Port-de-Paix on the northern coast of the island to begin your survey. You find an interesting group

of anolid lizards living in the vegetation adjacent to the beach. The temperature is 30 C, the relative humidity is

73%, and the locality is at sea level (barometric pressure = 760 mmHg). What is the partial pressure of carbon

dioxide in the air?

2) You begin trekking inland and discover a small freshwater lake that is inhabited by a diverse assemblage of

aquatic crustaceans. The elevation is 1815m (barometric pressure = 610 mmHg), the relative humidity is 62% and

the temperature is 20 C. What is the tension of nitrogen of the water in the lake?

3) You continue travelling inland and ascend the highest mountain, Morne de la Selle (2715 meters, barometric

pressure = 545 mmHg). At the top you discover a small pond that is inhabited by an unusual small fish species.

The temperature is 15 C and the relative humidity is 85%. What is the oxygen content (ml O2/liter water) of the

water in the pond?

4) Before departing Haiti you receive an invitation from a colleague to join her in the Aquarius underwater habitat

that is currently situated at 10 meters depth on the seafloor near the Ile de la Tortue, north of Port-de-Paix. She is

conducting experiments on corals in the surrounding patch reef area. The Aquarius habitat has open ports in the

bottom through which divers can enter the water, so the internal pressure in the habitat is the same as the ambient

pressure at that depth (1520 mmHg, relative humidity =100%, temperature = 20 C) and normal atmospheric air is

pumped down to the habitat from the surface. What is the partial pressure of nitrogen in the habitat?

Name _________________________________________ 2

The Aquarius habitat includes a small laboratory in which your colleague has installed aquaria to maintain the coral

specimens. The aquaria, which are filled with seawater, are equilibrated with the ambient air. Freshwater for

drinking and washing is kept in a large tank in the habitat and is also equilibrated with the ambient air in the

chamber.

5)_____ The tension of oxygen in the seawater in the aquaria would be (a. greater than; b. less than; c. equal to)

the freshwater in the tank.

6)_____ The oxygen content of the seawater in the aquaria would be (a. greater than; b. less than; c. equal to) the

freshwater in the storage tank.

7)_____ The tension of oxygen in the seawater in the aquaria would be (a. greater than; b. less than; c. equal to)

the tension of oxygen in the seawater surrounding the habitat at that depth.

Write the letter of the correct answer in the blank on the left side of the page (2 points each).

8)_____ In a mammalian circulatory system, the lowest pressure would be found in the (a. aorta; b. capillaries; c.

veins; d. vena cava.)

9)_____ The rate of diffusion of oxygen in air is (a. greater than; b. less than; c. equal to) the rate of diffusion of

oxygen in water.

10)____If the colloidal osmotic pressure is 30 mmHg and the hydrostatic pressure at a particular point in the

capillary is 22 mmHg, one would expect (a. reabsorption; b. no fluid movement; c. bulk filtration) to

occur at that point.

11)_____ During the “closed” phase of the cyclical respiration in insects, the partial pressure of oxygen in the

tracheal system (a. increases; b. decreases; c. remains relatively constant).

12)_____ Suppose that you perform an experiment on a mammal in which you decrease the oxygen content in the

inhaled air by 2.5%. You would predict that respiration by the animal would (a. increase; b. decrease; c.

remain unchanged).

13)_____ During exhalation, most of the air leaving the anterior air sacs of a bird (a. exits the mouth; b. enters the

posterior air sacs; c. flows into the lungs).

14)_____ The apparent viscosity of blood (a. increases; b. decreases; c. does not change) as the blood flows from

the arterioles to the capillaries.

15)_____ During inhalation, air flows from the (a. lungs; b. posterior air sacs; c. mouth) of a bird into the anterior

air sacs.

16)_____ If you monitored the pressure in the tracheal system of an insect, you would observe the lowest pressure,

relative to ambient, during the (a. fluttering phase; b. closed phase; c. open phase)

17)_____ Respiratory pigment molecules that are enclosed in blood cells tend to have a molecular weight that is (a.

greater than; b. less than; c. equal to) the molecular weight of respiratory pigments that are in solution in

the blood.

18)_____ At the normal pH of mammalian blood, most of the total carbon dioxide present is in the form of (a.

carbonic acid; b. bicarbonate ion; c. carbonate ion; d. a dissolved gas).

19)_____ Nearly 70% of the fat free vertebrate body is water. The smallest percentage of the water is found in the

(a. intracellular; b. interstitial; c. blood) compartment.

Name _________________________________________ 3

Oxygen-hemoglobin dissociation curves (a, b, & c) are graphed below. Fill in the blank with the letter

indicating the correct curve or with the correct value (2 points per blank)

20) If curve b is for the blood of a fetal

mammal, curve _____ is most likely for

the blood of the mother.

21) If curve b is for the blood of a rhinoceros,

curve _____ is most likely for the

myoglobin of its muscle.

22) If you increased the pH of a sample of

blood, curve b would shift towards

curve _____.

23) If the concentration of ATP in a blood

sample decreases, the oxygen

dissociation curve would be expected to

shift from the position of curve b

towards the position of curve _____.

24) The approximate P50 for curve c is _____

25) Suppose that you measure the oxygen

dissociation curves for a giraffe, a

gerbil and a gopher. Curve ____ is

most likely the curve for the giraffe.

26) If curve b was obtained for a blood sample tested at 30ºC, curve _____ would be obtained when the blood

sample is tested at 15 ºC.

27) If curve b is for blood leaving the muscle of a swimming fish, curve _____ would be the same blood after

leaving the gills.

28) If the blood sample shown by curve b was exposed to air with a high partial pressure of CO2, the curve would

be expected to shift toward the position of curve _____.

29) If curve b is for the blood of a deer, curve _____ is most likely for the blood of a seal of the same body mass.

The flow of blood through a portion of an unusual circulatory system is illustrated below. Fill in the blanks with the

number identifying the correct answer from the list below. The fluid has viscosity (i.e., it is not an ideal

fluid). (2 points per blank)

1. greater than 2. less than 3. equal to 30) The velocity at point B is _____ that at point C.

31) The pressure at point A is _____ that at point C.

32) In five minutes, the volume of water flowing past point A is ____ that at point B.

33) The tension in the wall at point B is ______ that at point D.

34) If the blood is stationary for a moment, the pressure at point C is ____ that at point D.

(You are viewing the vessels of the circulatory system from the side so point D is lower than point C.)

35) _____ Suppose that there is a mutation in mice that dramatically reduces surfactant secretion in the lungs. One

would predict that the muscular effort required to inflate the lungs during inhalation would (a. increase; b.

decrease; c. be unchanged) compared with a wild type mouse.

A B

C

D

% Sat

100

40 80

PO2 (mmHg)

a b c

Name _________________________________________ 4

36) _____ Suppose that you measured the breathing rate of a kangaroo (number of breaths per minute) while

hopping at sea level and while hopping at high altitude. If the stride frequency (number of hops per

minute) is identical at sea level and at altitude, you would predict that the breathing rate at altitude would

be (a. greater than; b. less than; c. equal to) that at sea level.

37) _____The lowest blood velocity in a mammalian circulatory system would be found in the (a. aorta; b.

capillaries; c. veins; d. vena cava.)

38) _____ The carbon dioxide content of air in the posterior air sacs of a bird is likely to be (a. greater than; b.

less than; c. equal to) that of the anterior air sacs.

39) _____ When compared at the same carbon dioxide tension, deoxygenated blood binds (a. more; b. less; c.

the same amount of) carbon dioxide compared with oxygenated blood.

40) _____ Suppose that you are a respiratory physiologist interested in the function of fish gills. You are also

unusually skilled in surgical techniques. You perform a series of experiments in which you swap the

arterial blood supply to, and venous return from, each gill arch so that blood flow through the gill lamellae

is reversed compared to the control fish. All other aspects of the experimental and control fish are

identical. You would predict that oxygen extraction in the experimental fish would be (a. greater than; b.

less than; c. equal to) that of the control fish.

41) _____ Suppose that you decide to repeat Scholander’s famous experiments on facilitated diffusion. If you

added gelatin to the hemoglobin solution you predict that the facilitation would (a. increase; b. decrease; c.

be unaffected).

42) _____ Gas exchange through the skin of most reptiles (a. is much greater than; b. is much less than; c. is

approximately equal to) gas exchange in the lungs.

43) _____ During the “fluttering” phase of cyclical respiration in insects, the partial pressure of carbon dioxide in

the tracheal system (a. increases; b. decreases; c. remains relatively constant).

44) _____ When carbon dioxide dissolves in water, the formation of (a. carbonate ion; b. bicarbonate ion; c.

carbonic acid) is the rate-limiting step. This step is accelerated by the enzyme called

45) ____________________________________________.

Fill in the blank with the correct word or words (2 points per blank).

46) If a gill removes oxygen from completely still water, the immediately adjacent

___________________________________ of water will soon be depleted of oxygen. Renewal of this

water is therefore important in supplying oxygen.

47) The tubeworm, Riftia pachyptilia, is an important member of many deep sea rift communities. Although it

lacks a mouth and intestinal tract, it grows remarkably rapidly and to great size. A large organ called the

___________________________________ fills the greater part of the coelom and is packed with bacteria

which provide the tubeworm with energy obtained from the oxidation of hydrogen sulfide.

48) In birds, the finest branches of the respiratory system, known as ________________________________ permit

through passage of air and are the site of exchange of the respiratory gases with the blood.

49) In insects, the openings of the tracheal system to the outside are called

__________________________________ and are highly complex structures that can be opened or closed

to allow a variable amount of gas exchange.

50) The flow of a fluid such as blood, water or air is characterized by two radically different regimes. In

_______________________________ the fluid “particles” move more or less parallel to one another in

paths that are smooth and regular. The large and small scale movements of the fluid in this regime are the

same.

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