lec 8

Question 1

in a forest, why might there more rabbits than moose?

Answer 1

smaller animals require less food –> more ecologically sustainable to have many small animals rather than many large animals

Question 2

what is the amount of energy passed down in the food pyramid? where does the rest of this energy go?

Answer 2

about 10% energy moves up trophic levels; the rest is lost to heat produced by metabolism [what about ectotherms?]

Question 3

what was lavoisier direct calorimeter? what did it demonstrate?

Answer 3

calorimeter lined w ice and place a small dude in there. the heat radiated from the small dude’s body melts the ice, illustrating metabolic rate

Question 4

what is the respiratory quotient (RQ)? what does an RQ of 0.9 tell us, compared to an RQ of 0.7?

Answer 4

ratio of carbon dioxide produced to oxygen consumed by the body

if we go off the classic glucose burning equation, we known the ratio is 6 O2:6 CO2 –> 1:1 ratio

if more O2 is used (ie metabolism accelerates) the ratio goes down

RQ = 0.9 tells us relatively lower metabolism = mostly glucose based diet

RQ = 0.7 tells us relatively higher metabolism = mostly lipid based diet

Question 5

how do metabolic rates change in different temperatures?

Answer 5

in hotter temps, metabolism goes up –> we sweat more (act of sweating requires energy)
in colder temps, metabolism goes down –> produce more heat [???]

Question 6

what is specific dynamic action? how can it mess with an experiment?

Answer 6

a period after eating where metabolism rises. if ur looking to study metabolism, u have to wait until the SDA period finishes to properly look at resting (basal) metabolism rate

Question 7

does predicted BMR match actual BMR? why/why not?

Answer 7

actual BMR is lower than theoretical BMR - as u get larger, it becomes harder for heat to escape (higher surface area:volume ratio). animals must account for this fact, or risk overheating in warmer conditions/risk heat not reaching extremities fast enough in colder conditions.

Question 8

what is allometric scaling?

Answer 8

body weight does not linearly correlate with metabolic rate due to underlying physiological responses

Question 9

which are more energetically expensive: ectotherms or endotherms? why?

Answer 9

endotherms, since they regulate their own heat, which requires lots of energy

Question 10

what is the relationship between heart size and heart rate?

Answer 10

as the heart increases in size, heart rate decreases
bigger size indicates more cardiac muscle, which must pump more efficiently