EEOB410
6th week’s discussion questions
1. An argument of some creationists states that evolution is impossible because it
defies the second law of thermodynamics. They state that molecules should not
form the ordered structures seen in organisms. Instead, the second law of
thermodynamics dictates that the molecules on earth should become more
disordered. Based on your knowledge of the second law, what is the flaw in this
argument?
2. Outline the flow and eventual fates of energy in this animal by labeling (OR
explaining in words) this diagram, similar to figure 6.2 in HWA. Is this animal an
open or a closed system?
3. What is the difference between direct and indirect calorimetry?
4.
What is the overall reaction for the complete oxidation of glucose?
5. What is the respiratory quotient (RQ), and why is it different for different
foodstuffs?
6. If an animal exhibits an RQ value of 0.83, what is it likely oxidizing? How do we
know (or not know!)?
7. Discuss the differences between basal, standard, and resting metabolic rate.
EEOB410
6th week’s discussion questions
8. As a new student in a physiology lab, you are studying metabolism in birds. You
arrive in the lab around 10:00 a.m. and feed the birds. As you are feeding the
birds, you notice that it is quite chilly in the room, causing you to shiver slightly.
As soon as you finish this task, you tell your advisor that you plan to measure the
basal metabolic rate of these birds immediately. Your advisor tells you that there
are at least 3 flaws in your experimental setup. What are these flaws, and how
might you correct them?
Metabolic Rate
9. Place the following labels on the graph below: thermoneutral zone, upper critical
temperature, lower critical temperature. Define each term.
Temperature
10.
a. Your lab does research using meadow voles as test subjects. As the
undergraduate in the lab, you are charged with taking care of these voles. You feed
the 30g voles about 175g of food per week. Your advisor gets curious about other
animals as test subjects, and traps some meadow jumping mice. These mice weigh
approximately 15g. You feed the jumping mice 87.5g of food per week, exactly half
of what you fed the voles. Will the jumping mice be healthy on this diet? Why or
why not?
b. Using figure 6.9 from your book, calculate the expected mass specific
metabolic rate of the meadow vole and the meadow jumping mouse.
EEOB410
6th week’s discussion questions
11. Dune Larks reside in the Namib Desert, one of the driest regions on earth. For Dune
Larks with an average body mass of 27.3 g, BMR equals 74.7 mL O2/h or 36.0 kJ/d.
Below 30 C, total evaporative water loss (TEWL) varied little with ambient temperature
(Ta) and averaged 66.0 mg H2O/h, or 1.58 g/day. Above 30 C, TEWL was described by
the equation mg
H2O/h = e-0.164 + 0.161(Ta). Between -3.9 and 35 C, body temperature did not vary and
averaged 40.8 C. Above 35 C, Tb increased linearly with Ta and was described by the
equation
Tb = 35.1 + 0.2 (Ta).
Below the lower critical temperature, oxygen consumption of Dune Larks was
described by ml O2/h = 201.95 - 4.56(Ta). Above the thermal neutral zone, oxygen
consumption was described as ml O2/h = -118.1 + 5.5(Ta).
a. What is the upper and lower critical temperature of Dune Larks? (Hint: use the
equations for metabolism at upper and lower temperatures to solve for the critical temps)
b. Construct a graph of metabolism vs. Ta and TEWL vs Ta. Notice that there are three
lines that you can graph. 1. A line for metabolism below the lower critical temperature, a
line for BMR, and a line above the upper critical temperature. Note that the intersection
of these lines will provide information about Tlc and Tuc.
c. Calculate the heat transfer coefficient H at 15 C, at 30 C, and at 45 C. When Ta > Tb,
should the bird minimize h or maximize h? Recall that 20.08 J of heat are produced per
ml oxygen consumed and that 2.4 J of heat are lost per mg water lost as evaporation.
d. At what temperature does Ta = Tb?
12. Why is it important to use isotopes for both hydrogen and oxygen in the doubly
labeled water method?
13. Suppose that under the conditions sufficient to measure basal metabolic rate, a
kangaroo rat consumes 2 mL O2/g*hr. You force this kangaroo rat to run on a
wheel until it is exhausted, and find that its maximum O2 consumption (VO2 Max)
was 14 mL O2/g*hr. What is the aerobic scope for this animal? What is its
aerobic expansibility?
14. Bar-tailed Godwits are currently recognized as the record holders among birds for
the longest non-stop flight during migration. This species takes an oceanic route from its
breeding grounds in Alaska and Russia to its wintering grounds in New Zealand. One
individual was tracked as traveling 11,026 km (6,851 miles) over the course of 9 days!
A closely related species, the Hudsonian Godwit, also breeds in Alaska, but takes an
overland route on its trip south, making stops to feed along the way. How might we
EEOB410
6th week’s discussion questions
expect the optimal speed of travel to differ between these two species during migration?
15. Suppose the heat of metabolism is 2,681.7 J/h, and the heat lost by evaporation is
160.2 J/h. At a body temperature of 40.8 C and an ambient temperature of 15 C, what is
the heat transfer coefficient?
16. What physiological parameters might we expect to change in a person who
undergoes endurance training?
17. Many people who feed birds in their backyard will put out suet (beef fat) in addition
to seeds for the birds to eat. During the winter months, the birds consume the suet much
more quickly than they do during other times of the year. Why might this be so in terms
of ecological energetics?