Chapter 15(a) Part 1; Energy Balance

Question 1

1st and 2nd laws of thermodynamics

Answer 1

1) energy cannot be created or destroyed, but it can be recycled in a closed system 2) a system and surroundings tend to degrade toward entropy. - Energy can help maintain order within a living system, at the expense of surroundings.

Question 2

In biological terms, energy is the capacity to ___ ___

Answer 2

increase order. We are constantly trying to work against entropy

Question 3

what is metabolism

Answer 3

process of transforming energy release into performance of functions.

Question 4

according to the energy budget, there is a selection pressure on animals to increase ___ and reduct ___

Answer 4

increase intake and reduce output (internal and external work)

Question 5

Explain polar bear energetics and conservation, and how energy stores predict population validity.

Answer 5

polar bears get fat during winter on the ice then fast for 8 months to rear their young. the energy store (fat) during ice breakup predicts population viability. As the ice-off date gets eariler in the year, the number of pups produced decreases.

Question 6

What is the index of energy consumption?

Answer 6

translates the consumption of energy at a cellular level to something measureable at the whole animal level.

Question 7

in order to allow for comparisons, ___ ___ must be applied to all measurements

Answer 7

standardized conditions.

Question 8

What is the standard metabolic rate ( in an ectotherm)

Answer 8

the minimum cost of existance or maintenance at a GIVEN TEMPERATURE

Question 10

What is the endothermic version of the standard metabolic rate? Problem with basal metabolic rate?

Answer 10

The basal metabolic rate. Essentially the minimum cost of existance or maintenance in an endotherm (something that maintains its own body temperature against ambient). this number isn’t super accurate because BMR must be calculated under very strict conditions. the animal cannot be exerting itself in any way.

Question 11

Energy output is considered to be ___ work and ___ work. All energy output eventually is lost as ____.

Answer 11

External work: the energy ex- pended when skeletal muscles are contracted to move exter- nal objects or to move the body in relation to the environment.

Internal work: all other forms of biological energy expenditure that do not accomplish mechanical work outside the body.

Both internal and external work is eventually lost in the form of heat.

Question 12

For an animal to be in an energy balance, energy input must = energy _____, which is measured as:

Answer 12

Energy input must equal energy output, which is measured as metabolic rates
of basal metabolism,activity, diet-inducedthermogenesis, and production

Question 13

general equation for metabolic rate

Answer 13

metabolic rate = energy expenditure/unit time

Question 14

what conditions must be maintained in order to measure BMR (in endoththerms) or SMR (in ectotherms) (6 things)

Answer 14

the organism must be:

1) non growing
2) non reproductive
3) non stressed
4) resting
5) thermoneutral temps
6) post -absorptive (not digesting)

Question 15

what is diet induced thermogenesis?

Answer 15

also known as heat increment feeding. the metabolic rate goes up 30-50% after feeding in mammals. This heat may be used as thermoregulative tools.

ex/ in little brown bats, the bats metabolic rate increased when they ate a full meal and they could not go into torpor because their body temperature was still high. therefore, eating creates diet-induced thermogenesis and temperature is maintained

Question 16

energy output in animals can also be measured by production, which is:

what kind of work is this?

Answer 16

Production refers to the rate of energy storage, such as adipose deposition, net growth during development, and reproduction (all internal work).

Question 17

BMR is hard to quantify for some animals. for example, its impossible for a rat to be in “resting state” and “post absorptive” at the same time. they will always be acative when they ar hungry. Instead, how is their metabolism measured?

Answer 17

by resting metabolic rate (RMRt) t= at a given temperature

Question 18

what is the maximum metabolic rate

Answer 18

the highest possible metabolism that is able to be sustained (ex/ metabolism when running, flying or shivering). typically a multiple of BMR

Question 19

What is field metabolic rate? How is it quantified?

Answer 19

Metabolic rate of a free range animal demonstrate NORMAL BEHAVIOR. it is measured by ISOTOPE TURNOVER.

Question 20

the measurement of whole animal metabolism requires some sort of ___ ___

Answer 20

metabolic index.

ex/ comparisons among species, comparisons among members, measuring costs of particular functions etc

Question 21

What makes up whole animal metabolism and how is this “allocated”?

Answer 21

heat makes up whole animal metabolism

• 50% lost as heat immediately during ATP synthesis

another 25% is lost during ATP expenditure

25% is turned into heat mechanically (ex/ friction of pumping blood)

Question 22

most common way of measuring energy turnover

Answer 22

by measuring heat production

Question 23

how do you directly measure the heat produced by an organism? How is this conducted? Why is this not practical?

Answer 23

Calorimetry.

Involves placing the subject in an insulated chamber with H2O circulating through the walls. The difference in the temperature of the H2O entering and leaving the chamber reflects the amount of heat liberated by the subject.

Not practical, because a calorimeter chamber can be costly, particularly for large animals.

Question 24

the metabolic rate is essentially “energy consumed/time,” which can be measured as __ ___/time

Answer 24

heat produced/ time

Question 25

True definition of a calorie

Answer 25

the amount of energy needed to raise the temperature of 1 gram of water by 1 degree C

Question 26

What is a joule? How many joules in a calorie

Answer 26

1 joule= work done by force of 1 N thorugh 1 meter (can be converted to heat)

1 calorie = 0.239J

Question 27

In order to directly measure the heat produced by an animal via calorimetry, you meausre the __ ___ of ___

Answer 27

latent heat of fusion, which is about 334J/g of ice at 0 degrees. If you melt 370g ice in 10 hours, than you know you burned 12358J/hr.

this is very tough to do and is often inaccurate

Question 28

Respiratory method is an ___ measurement of heat based on ___ consumption and ___ production. What is essentially measured here?

Answer 28

Respiratory measurements is an INDIRECT measurement of heat based on O2 consumption and CO2 production. By measuring O2 consumption, we are measuring VO2.

Recall that food energy is liberated with the use of oxygen during aerobic metabolism. Accordingly, a direct relationship exists between the volume of O2 used and the quantity of heat produced.

Question 30

what is stop flow respirometry

Answer 30

a type of indirect measurement of metabolic rate that involves cutting off air supply into each chamber. The animal then takes up O2 and released CO2, which you measure. You give some fresh air before conditions get hypoxic, which is moitored by the Mass-Flow Controller (MFC), which controls the pump

Question 31

Why is measuring O2 consumption not entirelyyyy effective at measureing true metabolic rate?

Answer 31

because there are other sources of energy and oxygen in the body:

1) anaerobic respiration is occuring furing bursting activity
2) use of stored energy and stored O2 (ex/ O2 in myoglobin)
3) energy yield per unit O2 consumed varies with substrate (ex/ carbs vs fat)

Question 32

generally, O2 consumption is pretty indicative of metabolic rate (minus anaerobic metabolism and previous myoglobin O2 stores). What are other indices of metabolic rate?

Answer 32

1) mass balance: intake and excretion
2) heart rate telemetry: Hr coorelates with MR
3) body temperature: ectotherms and endotherms

Question 33

In order to accurately allow aerobic metabolism to link heat production and O2 consumption, you most know the ___ ___ ____.

Answer 33

Respiratory exchange ratio (or respiratory quotion on a cellular lecl). the amount of heat//energy produced per a certain amount of O2 is dependent on what nutrient is being burned.

Question 35

What is the difference between RER and RQ and what is this value dependent on ? Which energy source has the lowest RER?

Answer 35

RER= resting exchange ratio for the whole animal. VolCO2/VolO2 for a given energy source. FAT has the lowest RER (0.7) because there are less CO bonds than other energy sources, such as carbs. Therefore, fat would produce less CO2 for a given amount of O2 used in a burning process.

Question 36

typical, C-___ bonds are the largest sources of energy in ingested food.

Answer 36

Carbon-hydrogen bonds

Question 37

doubly labelled water process determines ___ metabolic rate

Answer 37

field metabolic rate, which is the cost of actually living (ex/ eating, moving around)

Question 38

explain the reaction used in doubly labelled water experiments and outline the procedure.

Answer 38

principle of DLW poses that if we can track rate of CO2 production we can convert to heat production, assuming proper RERs.

uses the: bicarbonate buffer system reaction:

H2O+ CO2 –> H2CO3 –> H+ + HCO3-

1. catch animal and inject ²H₂¹⁸O isotopes.
2. take a T1 blood sample and release the animal. Let it do animal things. Catch the animal again and re sample with T2.
3. radioactive O is lost from the body as water and carbon dioxide, but H is only lost in H2O. Therefore, the difference in RATE OF H and O loss is due to CO2 production
4. plot T1 and T2 values on graphs measuring the amount of ¹⁸O and²H present in the samples. The slopes of each graph is either H loss in water or O loss in water and CO2.
5. Calculate CO2 produced.

Question 39

what is the maximum metabolic rate? metabolic scope?

Answer 39

max metabolic rate is the MR when an individual is running/flying/exerting themselves.

Metabolic scope: ratio of BMR or SMR (in ectotherms) to maximum MR.

**recall: BMR and SMR are measures of minimum metabolic rate.

Typically, the metabolic scope is 5-15 for most animals. This limit of 15 appears to reflect circulatory limits

Question 40

2 important factors that influence the rates of energy use

Answer 40

1) body size
2) temperature

Question 41

how does body mass influence MR? What is the mathematical relationship between mass and MR?

Answer 41

largery animals require more O2 overall than small animals, but smaller animals eats more (relative to body mass) than large animals, and thus more O2 is consumed on a PER GRAM basis in smaller animals.

Mr relation to body mass: MR=aW^b

Question 42

what is the surface hypothesis?

Answer 42

the idea posed by max rubner that the slope on a LOGSCALE graph of body mass and BMR is 0.67. MR=a(Mass)^0.67

On a log SA vs Log body mass graph, SA=a(mass)^0.67

there fore, more O2 is consumed in larger animals. (NOT on a per gram basis)

Question 44

What does a slope of <1 mean? What is the surface area to volume ratio?

Answer 44

slope of <1 means that the MR per unit BODY MASS DECREASES with INCREASING MASS.

SA= V^2/3

Surface area increases in proportion to volume as mass of an animal gets smaller. The larger animal loses less heat on surface because it has DECREASED Sa:Vol ratio.

Question 45

what is the specific metabolic rate mathematical relationship?

Answer 45

BMR/g= a(mass)-0.25

QUARTER POWER SCALING.

Larger animals consume less O2 per GRAM than smaller animals.

Question 47

2 problems with the surface area hypothesis

Answer 47

1) a slope of 0.67 for MR per unit mass isn’t really what’s found in nature – Kleiber posed that MR=a(mass)^0.75 instead.
2) this was supposed to only be for endotherms, because endotherms produce heat by their volumes (mass) and lose it from their surface areas, but ecotherms also demonstrate a trend with a slope less than 1. The hypothesis is irrelevant to most of these organisms, because most do not generate (and retain) body heat for the purposes of thermo- regulation.

Question 48

what is a posed reason that O2 consumption vs mass (MR=a(mass)^{0.75 or 0.67}) is 0.75 rather than 0.67?

Answer 48

some people pose that the MR= a(mass)^0.75 because of the fractal structures of a body. Energy is required for transport in these tubes, whcih scale to 3/4. This is properly not correct.

Some mammal BMR data does scale to 0.67, and some people think that Kleiber’s number (slope of 0.75) is messed up becauase large herbivores mess up the slope. It’s hard to get ungulates fully post-absorptive- they almost always have something in their gut, which might have elevated the MR. There may also be difference in Tb that is unaccounted for.

Question 49

what 4 things does the mtabolic theory of ecology attempt to explain?

Answer 49

1) MR scaling of all organisms
2) life history trats
3) population interactions: carrying capacity, competition and predation
4) ecosystem processes: productivity, trophic interactions, nutrient cycling

utilizes chemistry, physics and biology principles

Question 50

what is a trophic interaction

Answer 50

how much energy gets transferred from one trophic level to the next

Question 51

the metabolic theory of ecology relies on 3 things to explain complex ecological systems

Answer 51

1) relationship of MR and body mass
2) relationship of MR with temperature
3) stoichiometry: proportions of elements in reactions, organisms, ecosystems.

Question 52

combined reaction ( of body mass and temp factors) implemented in the metabolic theory of ecology.

Answer 52

they assume that the energy for fractal transport is proportional to a(mass)^0.75e^-E/kt

because energy for fractal transport is assumed to be MR:

MR= a(mass)^0.75e^-E/kt

where a(mass)^0.75= mass factor, and e^-E/kt= temperature dependence factor.

Question 53

According to the metabolic theory of ecology, what is the expression for size and temp dependence of mass-specific meatbolic rate?

Answer 53

MR/g= a(mass)^-0.25e^-E/kt

^{recall that specific metabolic rate uses quarter-power scaling.}

Question 54

How does the metabolic model of acoustic signalling (according to metabolic theory of ecology) explain communication calls?

Answer 54

using metabolic principles, there are three predictions:

1) call FREQUENCY and RATE is proportional to muscle contraction rate and is therefore porportional to mass SPECIFIC metabolic rate

M^-0.25e^-E/kt

2) Call DURATION is proportional to 1/frequency and therefore proportional to 1/RATE or FREQUENCY and therefore M^0.25e^{E/kt (note exponent values are positive)}
3) call POWER is proportional to muscle power and is proportional to whole animal MR and body MASS. therefore, M^3/4e^-E/kt

that means, when adjusted for size and temperature, all animals transmit the same “energy of information.” A humpback whale sounds the same as a spring peeper, given it’s different size and body temperature. Basic physiological principles predict fundamental aspects of communcation signals.

Question 55

Main criticism behind the metabolic theory of ecology

Answer 55

the underlying causal assumption of the MR=0.75 relationship is flawed.

MR will only be limited by transport systems and fractal geometry during intense activity and not at basal conditions. Also, not all organisms have fractal transport systems. how can it apply to them?

even though there are criticisms to this theoyr, it highlights connects of physical properties and biological systems. It can provide a good null model for testing hypotheses. It has alos helped us understand that many ecosystem processes also scale with individual body mass and temperature.

Question 56

As an alternative to metabolic theory of ecology, Charles Darveau and Peter Hochachka proposed the ____ ___ theory. outline this theory

Answer 56

The idea that 3/4 power theory can be explained by what happens during basal metabolic theory.

Proposed that all basal conditions such as protein synthesis rate (=aM¹), Na+K+ ATPase rates (aM²), and rates of other transport systems average out to a BMR=aM^0.75, and that maximal conditions involving O2 breathing,circulation, ATP muscles etc results in a maximal metabolic rate of aM^0.85.

These difference between basal and maximal metabolic conditions can account for dfiferences in scaling between groups, and can be adjusted to account for activtiy when different factors drive metabolic rate.

Question 57

What is the dynamic energy budget model

Answer 57

an alternative to the metabolic theory of ecology. the idea that all organisms have to store energy on some time scale.

• organisms need to convert resources to “structure” or “reserves.” this structure costs energy (BMR), but reserve doesn’t. Structure maintenance scales with volume, and reserve mobilization scales with SA. Asbody size increases, reserve has to get proportionally bigger, and therefore, BMR scales with mass BELOW 1

Question 58

According to dynamic energy budget models, Structure maintenance scales with ____, and reserve mobilization scales with ____.

Answer 58

Structure maintenance scales with volume, and reserve mobilization scales with SA.

as body size increases, reserve has to get proportionally bigger. therefore, BMR scales with mass BELOW 1

Question 59

body mass and temperature tends to explain most of the variation in metabolic rate between organism, but what accounts for the left over variation in BMR? (5 potential factors)

*BMR= Body mass residuals

Answer 59

1) Phylogeny. organisms share similarity due to evolutionary history,
2) Diet: insect eaters tend to have lower BMRs, unpredicatable food supplies may also affect metabolic rate
3) geography: unpredictable environments change metabolism

**Low BMR is an adaptation for energy conservation in the face of unpredictability.

4) life history: the larger the litter size in some rodents, the higher the BMRs. The smaller the size of the rodent as a neonate, the higher the BMR
5) personality: studies with dogs found that personality does correlate with lifespan AND metabolizable energy intake (how much they eat).

Question 60

When BMR changes within individuals due to season/captivity changes or body condition, it is said that the individual is exhibiting ___ ___

Answer 60

phenotypic plasticity.