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UCalgary - BIOL 241 - Study Guide - Final

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UCalgary - BIOL 241 - Study Guide - Final

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background image Biology 241: Energy Flow in Biological Systems Final Study Guide Topic 10: Energy Budgets Different organisms & energy needs All organisms have the same categories for energy distribution 
(reproduction, activity, etc.), however the amount of energy they put 
into each category differs based on their needs
o Large animals (humans): very efficient
o Small animals (mice): Not very efficient
o Ectotherms (Snake): Most efficient, since it doesn’t put energy 
into homeostasis Mass – specific energy use:  o compares energy required per gram of organism (shows  organism efficiency) Daily energy budgets Energy in = Energy out o Energy in = Food (sun, meat)
o Energy
excretion  = Stuff that leaves your body (urine, feces, heat,  CO 2 , sweat) Energy input  = Energy RMR  + Energy activitty  + Energy growth  + Energy reproduction  Energy excretion o E RMR : Resting metabolic rate Energy constantly burned to maintain cells. Minimum 
energy needed to survive
o E activity : Movement o E production : E growth  + E reproduction Primary focus is on growing, once you’re done growing 
focus switched to reproduction, so these two are grouped 
o E assimilation  = E in  – E Excretion Energy available for us to use Retention time of food in gut Initially we have a negative value (which means we’ve used energy in 
digestion before obtaining energy)
background image Energy obtained then increases since we’ve done some work and can 
get some energy 
As organism gets larger, intestine size increases  o Increase in organism size = increased retention times
o Meat eaters = shorter retention times
o Veggie eaters = longer retention times
Measuring energy Measured via heat loss in Joules (J) or Kila Joules (KJ) Volume of O 2  consumed or volume of Co 2  produced E RMR RMR = Resting Metabolic Rate (includes thermoregulation) Measure RMR by calculating amount of energy/Time Energy dedicated to cell maintenance. This energy needed to survive, 
o Used for maintenance, homeostasis, metabolism Factors that influence resting metabolism o Ambient temperature, Altitude, Diet, Stress, Physical size,  Activity level RMR differences among organisms o Larger animals have larger RMR than small animals, but increase is not linear o Small animals: large surface area to volume ration
o Large animals: Small surface area to volume ratio
o Surface area dependent
Heat loss Gas exchange Food absorption Linear scale issues Most organisms are small, and focused near the bottom of the graph Few animals are large, and further from the rest of the data Logging y or x-axis spreads out small numbers, and condenses large 
Straight lines also let us calculate o x and y-intercepts, and slopes Metabolic rate scaling with mass -Hypothesis 1: RMR scales with mass in proportion to how surface area 
scales with volume
In this hypothesis, our:
background image o Mass is approximately equal to volume
o RMR is equal to Log surface area
o If the above is true, the slope would be equal to 0.67
-Hypothesis 2: RMR scales with mass in proportion to how volume scales with
In this hypothesis, the slope would be equal to 1 -Actual slope found In-between 2 hypotheses, it was 0.75. This is called the ¾ power law, 
or Kliebers law
When given a graph where we see RMR compared to mass, we see o All have approximately the same slope (0.75)
o In similarly massed endotherms and ectotherms, the endotherm 
will have a RMR about 10x more than the ectotherm Mass-specific metabolic rate Mass-specific metabolic rate: MR/M (metabolic rate/ mass) Larger organisms much more efficient with energy than small 
When going from an absolute metabolic rate to a mass specific scale, 
both log transformed, subtract 1 from exponent. To go from a mass 
specific scale to an absolute log scale, add 1 to the exponent
E production  (Energy growth and reproduction) E Growth o Organisms getting larger E reproduction   o Making offspring Two terms merged together, since only working on one at a time If Eproduction is positive, the energy is diverted to reproduction If Eproduction is negative, there isn’t enough energy for reproduction  Topic 11: Energy and homeostasis Homeostasis Regulation of internal environment in the face of changes in the 
external environment 
Positive feedback mechanisms Stimulus  sensor  effector  response o This makes the stimulus even stronger
background image In positive feedback, the difference is accelerated. Positive feedback 
pushes an organism further away from “normal”. 
o When pregnant, you have contractions, the contractions send  signals to the brain which cause longer, harder contractions Negative feedback mechanisms Stimulus  sensor  effector  response o Maintains a system at normal levels by opposing stimulus Compares environment stimuli with a “set point” or “Normal”. We 
fluctuate around set point, not always consistent 
Cold  thermostat  heater  heat o An increase in heat effects sensor, once it senses an increase in  heat, it tells the heater (effector) to stop producing heat Organisms gain and lose heat to environment Conductions o Heat exchange through direct contact Convection o Heat exchange through moving medium (gas, air) Evaporation o Heat loss through state change Radiation o Heat exchange through infrared emission or absorption Conductance  o The rate (J/time) of heat loss Body temperature regulation strategies Homeotherm o “Constant” body temperature (Tb) regardless of ambient  temperature (Ta) Heterotherm o Tb varies with Ta Endotherm o Tb is dependent on internal metabolism Ectotherm o Tb is dependent on external sources  Ambient Temperature (Ta) and metabolic rate (RMR) in a homeothermic 
Large range of temperature where they are not putting any energy into
thermoregulation. This range of ambient temperature is called the 
“Thermo neutral zone”

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School: University of Calgary
Department: OTHER
Course: Energy Flow in Biological Systems
Professor: William Huddleston
Term: Fall 2017
Name: Biology 241 - Final Study Guide
Description: This study guide covers the material that will be on the lecture final
Uploaded: 12/11/2017
15 Pages 95 Views 76 Unlocks
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