BIOL 241 Final Exam Questions With
Complete Answers
Homeostasis - ANSWER Internal environment must be regulated as external
environment changes. (pH, water, temperature, blood volume, etc... must be regulated).
Negative Feedback - ANSWER Triggers a response that opposes change (returns an
organism to a set point). ex. heating system in your house.
Positive Feedback - ANSWER Triggers a response that reinforces change (pushes
system farther away from the set point). ex. baby pushes on uterus --> stretch receptors
notice --> Oxytocin released --> uterus contracts.
Thermoregulation - ANSWER -Important for all organisms to regulate their internal body
temperature.
-Ambient Temp (Ta): temp of surroundings.
-Body Temp (Tb): temp of system.
Body Heat - ANSWER -Generated by metabolism.
-Heat flows hot to cold.
-Exchanged by conductance/convection/radiation.
Conductance - ANSWER -The rate of heat exchange.
-Small organisms have high conductance.
-Long fur = low conductance.
-Body size and fur thickness affect conductance.
Homeotherm - ANSWER Maintain constant body temp independent of Ta. (ex.
Humans).
Poikilotherm - ANSWER Body temp fluctuates with Ta. (ex. freshwater fish are warmer
in summer than winter).
Endotherm - ANSWER Generate body heat through metabolism...internal heat
generation.
, Ectotherm - ANSWER Aquire body heat from the environment...external heat source.
Heterotherm - ANSWER A mix of endo and ecto therm body heat regulation.
Homeothermic Endotherms - ANSWER Birds and mammals use behavior and
physiology to regulate heat loss/gain with the environment.
-Slope is conductance...the steeper the line, the greater the conductance, the faster
hypothermia is reached.
-Shiver/hide/vasoconstriction to warm up.
-Sweat/pant/hide to cool down.
Poikilothermic Ectotherm - ANSWER Use both behavioral and physiological strategies
to regulate body temp. ex. fish, amphibians, reptiles, invertebrates.
Acclimation - ANSWER -Physiological changes occur in response to seasonal changes.
-Occurs in all organisms.
Exposure - ANSWER -Move in/out of the sun and wind.
-ex. vultures heat their wings in the morning
Grouping - ANSWER -Shared body heat keeps them warm
-ex. penguins huddling together
Dormancy (Torpor) - ANSWER At night, body temp drops. This lowers the set point for
a short period of time.
Dormancy (Hibernation) - ANSWER Body temp drops so that it becomes very close to
Ta. They can stay this way for weeks, and repeat this cycle for many months.
***bears do not hibernate, they enter winter sleep***
Migration - ANSWER Complete avoidance of poor environmental conditions.
Blood Flow - ANSWER Vasoconstriction: keeps heat from leaving.
Vasodilation:
-Endo: allows heat to leave
-Ecto: allows heat to enter
Insulation - ANSWER Internal: fat/blubber to reduce conductance.
External: fur/feathers to reduce conductance.
Coloration - ANSWER White fur allows solar radiation in, and black skin absorbs heat.
Sweating/Panting - ANSWER Heat loss due to evaporation (only horses and humans
really sweat).
Complete Answers
Homeostasis - ANSWER Internal environment must be regulated as external
environment changes. (pH, water, temperature, blood volume, etc... must be regulated).
Negative Feedback - ANSWER Triggers a response that opposes change (returns an
organism to a set point). ex. heating system in your house.
Positive Feedback - ANSWER Triggers a response that reinforces change (pushes
system farther away from the set point). ex. baby pushes on uterus --> stretch receptors
notice --> Oxytocin released --> uterus contracts.
Thermoregulation - ANSWER -Important for all organisms to regulate their internal body
temperature.
-Ambient Temp (Ta): temp of surroundings.
-Body Temp (Tb): temp of system.
Body Heat - ANSWER -Generated by metabolism.
-Heat flows hot to cold.
-Exchanged by conductance/convection/radiation.
Conductance - ANSWER -The rate of heat exchange.
-Small organisms have high conductance.
-Long fur = low conductance.
-Body size and fur thickness affect conductance.
Homeotherm - ANSWER Maintain constant body temp independent of Ta. (ex.
Humans).
Poikilotherm - ANSWER Body temp fluctuates with Ta. (ex. freshwater fish are warmer
in summer than winter).
Endotherm - ANSWER Generate body heat through metabolism...internal heat
generation.
, Ectotherm - ANSWER Aquire body heat from the environment...external heat source.
Heterotherm - ANSWER A mix of endo and ecto therm body heat regulation.
Homeothermic Endotherms - ANSWER Birds and mammals use behavior and
physiology to regulate heat loss/gain with the environment.
-Slope is conductance...the steeper the line, the greater the conductance, the faster
hypothermia is reached.
-Shiver/hide/vasoconstriction to warm up.
-Sweat/pant/hide to cool down.
Poikilothermic Ectotherm - ANSWER Use both behavioral and physiological strategies
to regulate body temp. ex. fish, amphibians, reptiles, invertebrates.
Acclimation - ANSWER -Physiological changes occur in response to seasonal changes.
-Occurs in all organisms.
Exposure - ANSWER -Move in/out of the sun and wind.
-ex. vultures heat their wings in the morning
Grouping - ANSWER -Shared body heat keeps them warm
-ex. penguins huddling together
Dormancy (Torpor) - ANSWER At night, body temp drops. This lowers the set point for
a short period of time.
Dormancy (Hibernation) - ANSWER Body temp drops so that it becomes very close to
Ta. They can stay this way for weeks, and repeat this cycle for many months.
***bears do not hibernate, they enter winter sleep***
Migration - ANSWER Complete avoidance of poor environmental conditions.
Blood Flow - ANSWER Vasoconstriction: keeps heat from leaving.
Vasodilation:
-Endo: allows heat to leave
-Ecto: allows heat to enter
Insulation - ANSWER Internal: fat/blubber to reduce conductance.
External: fur/feathers to reduce conductance.
Coloration - ANSWER White fur allows solar radiation in, and black skin absorbs heat.
Sweating/Panting - ANSWER Heat loss due to evaporation (only horses and humans
really sweat).
