Topic 7 - Energy Budgets Flashcards
What do organisms need energy for
Maintenance, rapid growth, reproduction, thermo-regulation
What factors do energy budgets depend on?
Size
Environment
Thermoregulation
How do energy demands differ between larger and smaller body mass
larger body mass needs more energy, but based on body mass, smaller organisms need more
How does body size influence energy demand
what behaviours are impacted
impacts how organisms move, how often they eat, what they eat
what is the SA to V ratio for smaller organisms compared to larger
smaller organisms have a higher ratio
does surface area scale with mass
yes because mass and volume are related
as mass increases, surface area increases
why is body size scaling important
explain for volume and more SA
organisms need to obtain resources and excrete waste to support their mass/volume
they exchange matter and generate energy across their membranes (SA)
what are the disadvantages of Large organisms with respect to SA:V ratio
reduced efficiency, longer diffusion distance, need for specialized system
lots of biomass needs to be maintained but there is limited SA, stuff needs to flow a long way from in to out, energy must be diverted to build and maintain systems to increase SA
what are the advantages of Large organisms with respect to SA:V ratio
Heat retention - heat is produced by entire volume but lost through minimal surface
Water conservation
Structural strength
Allometry
when biological phenomena do not vary linearly with body size
What are the reasons for allometry
need for structural support and how it changes with size - elephants need thicker bones to hande larger mass
Isometry
linear relationship between mass and a biological variable
Positive allometry (hyperallometry)
as one dimension increases, the other increases at a faster rate
Negative allometry (hypoallometry)
as one dimension increases the other increases at a slower rate
How does body size affect energy in
larger animals need more food, greater Ein per unit time, they eat less relative to body size,
they take in more air and pump more blood with each heartbeat - slower breathing and heart rate
why do larger animals eat less food per body weight
what characteristic differs between larger and smaller animals
smaller animals have higher metabolic rate so they eat more than their body weight
What are strategies to minimize energy lost through excretion (aka how do we increase assimilation)
chewing, selection of palatable foods, gut length, food retention time
What is MR
rate of energy consumption - rate at which chemical energy is converted to heat and work
RMR
energy expenditure at rest but routine activities
BMR
basal, metabolism at complete rest, lowest possible
SMR
standard
measured at specified temperature (ectotherms)
FMR
field, measured in wild animals
what is BMR used for
endotherms
metabolic rate while in TNZ
what is SMR used for
ectotherms when fasting/resting
