MBE 307 Exam 2 Qestions And Answers 2024/2025
What is the difference between ectotherms/poikilotherms and endotherms? - ANS-Ecotherms'
body temperatures are influenced by the ambient temperature (some poikilotherms can regulate
temperature) whereas endotherms are warmed by metabolic heat (home...
MBE 307 Exam 2 Qestions And Answers 2024/2025
What is the difference between ectotherms/poikilotherms and endotherms? - ANS-✔✔Ecotherms'
body temperatures are influenced by the ambient temperature (some poikilotherms can regulate
temperature) whereas endotherms are warmed by metabolic heat (homeotherms regulate by
physiological means).
How do moths and bees exhibit heterothermy? - ANS-✔✔Moths and bees must warm their muscles
first through shivering and muscle contractions in order to fly, thus they must heat their wings. They are
also hairy for insulation.
Explain and give examples of how climate change has influenced the physiology and ecology of
organisms. - ANS-✔✔Increasing temperature is causing the MMR to do down and the RMR to go up,
thus decreasing organism's aerobic scope. There is 30 days between egg laying and peak prey
abundance, but the changing temperature has caused peak prey abundance to be early, so birds are
now missing the timeline. Other examples include how Atlantic Cod are moving north because of
warming in the North Sea.
What is convection? - ANS-✔✔Convection is heat transfer carried by wind/water flow. It is a faster
macroscopic flow. Rate is given by thermal gradient and convection coefficient. An example is how
warm air rises to top of a building or ocean currents carrying heat.
What is conduction? Describe it and give examples. - ANS-✔✔Conduction is heat transfer through
direct contact. It is a slow heat diffusion with no macroscopic movement. Rate is given by thermal
gradient and conductivity. An example is the process of heating a pan or stove.
What is evaporation? - ANS-✔✔Evaporation is heat transfer when a liquid turns into a gas through the
latent heat of evaporation.
What is radiation? - ANS-✔✔Radiation is heat transfer by electromagnetic waves/light. Radiation
intensity is proportional to surface temperature. It can still happen without light, as all organisms and
things radiate heat. An example is the jackrabbit using its large ears to radiate heat and control blood
flow.
,Describe poikilotherms and ecotherms. How do they differ between aquatic and terrestrial animals? -
ANS-✔✔Ecothermy happens for most animals (not mammals or birds). Ecotherms depend on
environmental temperature but poikilotherms have some thermoregulating capabilities. Aquatic
ecotherms have body temperatures the same as the ambient environment since water is a strong
thermal conductor. For terrestrial animals, thermal radiation and evaporation can lead to a differential
temperature.
How do poikilotherms thermoregulate? What is eurythermal and stenothermal? - ANS-✔✔
Poikilotherms can thermoregulate through their behavior. Eurythermals can cope with a large range of
temperatures but are not optimized, whereas stenothermals optimize their physiology to a narrower
range of temperatures.
How do poikilotherms respond to temperatures on an acute scale? - ANS-✔✔Their chemical reactions
are faster at higher temperatures, giving an exponential relationship. This applies to a limited range of
temperature.
How do poikilotherms respond to temperatures on a chronic scale? Give examples. - ANS-✔✔They will
adjust their physiology to acclimate to their temperature. In two groups of lizards exposed to different
temperatures, the cold acclimated lizards had higher metabolic rates compared to the warm acclimated
lizards, even when temperature was varied acutely. Molluscs can also acclimate to temperature, as
molluscs in colder temperatures have a jetting speed similar to that of molluscs in high temperatures.
What are the thermal limits of poikilotherms? - ANS-✔✔Poikilotherms have a peak performance
temperature, but then their performance declines with increased or decreased temperature. Eventually,
this can lead to mortality. The aerobic scope of the organism will determine its fitness.
How to poikilotherms respond to changing temperatures on an evolutionary scale? Give examples. -
ANS-✔✔There may be thermal specialization in poikilotherms, as suggested by behavioral
thermoregulation. Temperature affects molecular conformation and therefore the functional properties
of molecules thermal adaptation means the evolution of different molecular forms of proteins. An
example is the eye lenses of the Antarctic toothfish. For most organisms, cold temperatures affect their
eye lens, as a cold cataract takes longer to form or won't form at all. But in the toothfish, the eye lens
forms normally.
, How do poikilotherms evolutionarily change their enzyme kinematics? - ANS-✔✔Enzyme
function/substrate affinity is temperature dependent, and kcat is also temperature sensitive and under
selection. Affinity typically decreases with temperature but all fish have similar enzyme affinities at their
preferred temperatures.
How do poikilotherms adjust their membrane fluidity? - ANS-✔✔Poikilotherms undergo homeoviscous
adaptation. At low temperatures, there are more unsaturated lipids, which bring disorder and fluidity to
fight the coldness. At high temperatures, there are more saturated lipids to fight the membrane from
falling apart.
How are poikilotherms threatened by freezing? How do poikilotherms inherently protect themselves? -
ANS-✔✔Animal body fluids have higher freezing points than seawater, and intracellular freezing can
cause death. Either there is slow gradual cooling or unstable, rapid freezing. When the extracellular
environment starts freezing, salts are excluded, giving a more concentrated extracellular environment.
The higher osmotic pressure causes water to leave the cell and shrink, but now the cell is more
concentrated so its freezing point lowers, thus serving as inherent protection.
What are some adaptive mechanisms to freezing conditions? - ANS-✔✔1.) Avoidance.
2.) Antifreeze compounds such as colligative antifreeze (glycerol, sorbitol) and noncolligative
compounds (antifreeze proteins that arrest ice nucleation by stabilizing ice crystals to slow down their
formation). This is common in many marine fish and insects.
3.) Supercooling through lowering the concentration of ice nucleating agents. Supercooling is the
process of cooling below the freezing point without becoming a solid.
4.) Freezing is common in amphibians and insects. They limit the degree of super cooling in extracellular
fluids, allowing for safe freezing, and synthesize ice nucleating agents. They have high levels of glycerol,
glucose, and urea.
Describe homeothermy and how it compares metabolically to poikilothermy. - ANS-✔✔Homeothermy
maintains a constant temperature across climate zones (though gets higher during active phases). Body
temperature is sensed through neurons and controlled by the hypothalamus. There is a 4-10 fold
difference in metabolic rate between poikilotherms and homeotherms at 37 C, and 15-30 fold different
in free living ones. Homeothermy is very costly, which is why poikilothermy is more common.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Accurate. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.19. You're not tied to anything after your purchase.
