I have a question Are tuna endotherm or ectotherm? I have ever studied that tuna is Homeotherm in ectotherm. Now I feel confused.

I found this online. "An *endotherm* is able to regulate its body temperature via metabolic processes, these are commonly known warm blooded animals. An *ectotherm's* body temperature is dictated by the environment surrounding it, the animals are commonly and incorrectly known as cold blooded. -- *Poikilotherms* are animals that do not require a fixed body temperature, their temperatures can fluctuate with little to no adverse effects to their overall health. Most terrestrial ectotherm's are poikilotherms, such as snakes and many lizards, also the naked mole rat is considered to be the only mammal poikilotherm. *Homeotherms* are animals that maintain a constant body temperature. All endotherms are homeothermic, but some ectotherms, like desert lizards, are so good at maintaining their body temperature with behavioral means that they are considered homeothermic." source: https://faculty.mtsac.edu/trevell/bio2/bio2resources/thermo

I have two questions. First, is the thermoneutral zone for humans around 24 Celsius or 37? And second, why do we feel hot when the environment temperature is 37 Celsius, when 37 is the temperature we want our body to have?

Thermoneutral zone for humans is around 24, not 37. The thermoneutral zone is defined as the range of ambient temperatures where the body can maintain its core temperature solely through regulating dry heat loss, i.e., skin blood flow. *This paper explains* https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4977175/ Why not 37? Because imagine even if we were nude at that temperature (anything above 30 is too much). Also while it is plausible for our basal metabolic rate, not suitable for _any_ kind of work. Have you noticed that slightest amount of work even at 27 makes you sweat? We feel hot because we are _not static objects_ which just conduct temperature. We also _produce_ temperature in our core, plus have a skin which is _an insulator_. So the reason why you feel hot at 37 is mainly that you have skin _whose surface temperature is lower than 37_ so your body surface is colder and starts absorbing environmental temperature.

Why would one expect the Q10 value of an ectotherm to be around 2?

If Q10 is 2 it means an increase in the surrounding temperature with an increase in 10 ◦C, and usually resulted in a doubling of the reaction rate. The Q10 values can be determined from the Arrhenius plots. (In chemical kinetics, an Arrhenius plot displays the logarithm of a reaction rate constant, (, ordinate axis) plotted against reciprocal of the temperature (, abscissa).) https://www.google.com/imgres?imgurl=https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2Ff%2Ff6%2FNO2_Arrhenius_k_against_T.svg%2F1200px-NO2_Arrhenius_k_against_T.svg.png&imgrefurl=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FArrhenius_plot&docid=knFyGYn7H893XM&tbnid=k3xTzrdU8e6HCM%3A&vet=10ahUKEwiC3IGzg8blAhUPKlAKHd82DDcQMwhNKAEwAQ..i&w=1200&h=912&bih=625&biw=1366&q=arrhenius%20plots%20for%20temperature&ved=0ahUKEwiC3IGzg8blAhUPKlAKHd82DDcQMwhNKAEwAQ&iact=mrc&uact=8 So I found the paper where Researchers have experimented on _Pseudomonas sp._ (ectotherm, relying upon external temperature) and phenol degradation was referent variable to detect metabolism of _Pseudomonas_. https://www.researchgate.net/publication/322925209_Estimation_of_the_Q10_value_the_Temperature_Coefficient_for_the_Growth_of_Pseudomonas_sp_AQ5-04_on_Phenol Again, your questions as *why is that so*? And I cannot tell you for sure _why_ the rate usually is 2, it was experimentally obtained and concluded. Probably it has to do something with Laws of Thermodynamics and logic. Think about it, if it was 3, 4, or 7, what would it mean in BIological terms?! That metabolism would be super fast, and at 30*C, the organism may just burn out in half an hour. And it does not make sense.

Which between a unicellular organism, ectotherm and endotherm has the highest BMR and which one is the lowest?

This is one of those questions that seem reasonable, but are so dependent on the specific organisms that they are probably impossible to get a useful answer for. For example, unicellular organisms are incredibly diverse (contain organisms from all three domains of life and from multiple eukaryotic kingdoms) — they will not have similar metabolic rates. Furthermore, unicellular organisms can't even all be grown at the same temperature — how would you meaningfully compare the metabolic rate of a marine bacterium that lives in arctic waters (prefers 4°C) vs. the rate for an archaebacterium that grows only on a "black smoker " (undersea thermal vent) and prefers 98°C (can grow at up to 122°C): https://ocean.si.edu/ecosystems/deep-sea/microbes-keep-hydrothermal-vents-pumping Another example, is what kind of endotherm — a blue whale? an elephant? a shrew? a hummingbird? an ostrich? ... Well, hopefully you found some of that rant interesting or at least mildly entertaining ...

Why does temperature affect the breathing and heart rates of ectothermic organisms?

Because temperature per se affects any kind of work. At higher temperatures, the working machine (or int his case heart) has to work harder and easier gets overheated. The same way temperature affects Ebdithersm, it also affects Ectitherms, especially because they _rely_ on the temperature. Because temperature directly correlates with metabolism rate. The greater the temperature faster the metabolism and vice versa. Here is one interesting paper depicting how also Ectotherms may have energy costs in their metabolisms because sudden increases and decreases impose some kind of stress on bodies. They are physiologically dependant on external temperature and their viability is reduced at extremes. https://www.sciencedirect.com/science/article/pii/030645659400023C

Main content

Course: Biology library > Unit 32

Lesson 2: Metabolism & thermoregulation

Endotherms & ectotherms

Google Classroom

The difference between endotherms and ectotherms. How to read graphs related to endotherms and ectotherms.

Key points

Most animals need to maintain their core body temperature within a relatively narrow range.
Endotherms use internally generated heat to maintain body temperature. Their body temperature tends to stay steady regardless of environment.
Ectotherms depend mainly on external heat sources, and their body temperature changes with the temperature of the environment.
Animals exchange heat with their environment through radiation, conduction—sometimes aided by convection—and evaporation.

Introduction

What’s it like outside today? If it’s winter where you are, it might be pretty cold. If it’s summer, it might be pretty hot. Either way, odds are that your core body temperature is right around

98.6^{\circ} F

37^{\circ} C

. As we saw in the article on homeostasis, mechanisms like shivering and sweating kick in when your body gets too cold or too hot, keeping your internal temperature steady.

Not all organisms keep their body temperature in as narrow a range as we humans do, but virtually every animal on the planet has to regulate body temperature to some degree—if only to keep the water in its cells from turning to ice or to avoid denaturing its metabolic enzymes with heat.

Broadly speaking, animals can be divided into two groups based on how they regulate body temperature: endotherms and ectotherms. Let's take a closer look at the difference between these two groups.

Endotherms and ectotherms

People, polar bears, penguins, and prairie dogs, like most other birds and mammals, are endotherms. Iguanas and rattlesnakes, like most other reptiles—along with most fishes, amphibians, and invertebrates—are ectotherms.

Endotherms generate most of the heat they need internally. When it's cold out, they increase metabolic heat production to keep their body temperature constant. Because of this, the internal body temperature of an endotherm is more or less independent of the temperature of the environment.

The sum total of the biochemical reactions that take place in an organism are called its metabolism. Metabolic reactions involve breaking down fuel molecules, such as sugars, and using the energy stored in them to do work. The processes that convert energy stored in food molecules into biological work are not very efficient, so heat is generated as a byproduct.

The higher an organism's metabolic rate—the amount of chemical fuel it burns in a given period of time—the more heat it will produce.

So, as an endotherm is exposed to colder external temperatures, it will increase its metabolic rate, burn more fuel, and produce extra heat to keep its body temperature constant.

This pattern is shown on the graph below: the mouse maintains a steady body temperature close to

37^{\circ} C

across a wide range of external temperatures.

Image credit: diagram based on data from Cannon and Nedergaard

^{1}

, Figure 2, and on similar figure in Purves et al.

^{2}

For ectotherms, on the other hand, body temperature mainly depends on external heat sources. That is, ectotherm body temperature rises and falls along with the temperature of the surrounding environment. Although ectotherms do generate some metabolic heat—like all living things—ectotherms can't increase this heat production to maintain a specific internal temperature.

Image credit: diagram based on theoretical graph from Meek

^{3}

, Figure 1 and on Akin

^{4}

, Figure 1

Most ectotherms do regulate their body temperature to some degree, though. They just don't do it by producing heat. Instead, they use other strategies, such as behavior—seeking sun, shade, etc.—to find environments whose temperature meets their needs.

Some species blur the line between endotherms and ectotherms. Animals that hibernate, for instance, are endothermic when they are active but resemble ectotherms when they are hibernating. Large fish like tuna and sharks generate and conserve enough heat to raise their body temperature above that of the surrounding water, but unlike a true endotherm, they don't maintain a specific body temperature. Even some insects can use metabolic heat to increase body temperature by contracting their flight muscles!

^{5, 6, 7}

One other important point: as a general rule, endotherms have considerably higher metabolic rates than ectotherms. That's because they have to burn large quantities of fuel—food—to maintain their internal body temperature.

Why regulate temperature?

There are some basic limits on survivable body temperature for most animals. At one end of the spectrum, water freezes at

32^{\circ} F

0^{\circ} C

to form ice. If ice crystals form inside a cell, they'll generally rupture its membranes. At the other end of the spectrum, enzymes and other proteins in cells often start to lose shape and function, or denature, at temperatures above

104^{\circ} F

40^{\circ} C

^{8}

Why do many organisms—including you and me—keep their body temperature in a narrower range than this? The rate of chemical reactions changes with temperature, both because temperature affects the rate of collisions between molecules and because the enzymes that control the reactions may be temperature-sensitive. Reactions tend to go faster with higher temperature, up to a point, beyond which their rate drops sharply as their enzymes denature.

Each species has its own network of metabolic reactions and set of enzymes optimized for a particular temperature range. By keeping body temperature in that target range, organisms ensure that their metabolic reactions run properly.

Temperature balance

For both endotherms and ectotherms, body temperature depends on the balance between heat generated by the organism and heat exchanged with—lost to or gained from—the environment.

Heat always moves from warmer to cooler objects, as described in the Second Law of Thermodynamics.

There are three main ways that an organism can exchange heat with its environment: radiation, conduction—along with convection—and evaporation.

Radiation: Radiation is the transfer of heat from a warmer object to a cooler one by infrared radiation, that is, without direct contact.
Conduction: Heat can be transferred between two objects in direct contact by means of conduction. Conduction of heat between your skin and nearby air or water is aided by convection, in which heat is transferred through movement of air or liquid.
Here are a couple of examples:
Conduction: If you pick up an ice cube, you'll lose heat to the ice by means of conduction. If you walk barefoot on stone on a sunny day, on the other hand, you'll absorb heat from the stone by conduction.
Convection: Wind helps move air away from your body by convection, bringing along new, cooler air and thus increasing the transfer of heat from skin to air. This makes us feel colder when it is windy out, something you may have experienced as wind chill.
Evaporation: Vaporization of water from a surface leads to loss of heat—for example, when sweat evaporates from your skin. To learn why this is the case, take a look at the Why does sweating cool you down? video.

How do organisms control heat production and heat exchange to maintain a healthy internal temperature? We'll answer just that question in the next article on temperature regulation strategies.

Check your understanding: graphs of metabolic rate

The graph below shows metabolic rate as a function of external temperature for two animals: an endotherm and an ectotherm.

Image credit: figure based on Hiebert and Noveral

^{9}

, Figure 1

Which curve represents the endotherm, and which represents the ectotherm?

We can use what we know about how endotherms and ectotherms maintain body temperature to figure out which line corresponds to which animal.

To start with, let's "translate" the Y axis of the graph. Oxygen consumption is a common measure of metabolic rate, because

O_{2}

gas is used up when fuel molecules are broken down during cellular respiration. The faster an organism is using up oxygen, the higher its metabolic rate. We could equally well measure

{CO}_{2}

production or heat production to determine metabolic rate.

So, which curve represents the endotherm? Endotherms increase their metabolic rate as temperature drops, producing more heat and thus keeping their internal temperature up. The only curve that goes up as temperature goes down is the upper curve—the blue curve

A

—so this must be the endotherm.

Image credit: based on Hiebert and Noveral

^{12}

, Figure 1, and Purves et al.

^{2}

The flat part of the curve corresponds to the thermoneutral zone—the range of external temperatures over which the endotherm doesn't have to expend extra energy above its basal, or resting, metabolic rate to maintain body temperature. The increase in metabolic rate at higher temperatures represents the expenditure of energy to try and cool the body, and/or the heating of tissue as cooling systems fail.

^{9}

The remaining curve—the red curve

B

—must be our ectotherm. Not only is the ectotherm's metabolic rate consistently lower than that of the endotherm, but it also drops as external temperature decreases—the opposite pattern from the endotherm. That's because biochemical reactions tend to slow down at low temperatures, such as those of an ectotherm's body when external temperature decreases.

Image credit: figure based on Hiebert and Noveral

^{12}

, Figure 1, and Purves et al.

^{2}

This article is licensed under a CC BY-NC-SA 4.0 license.

Works cited

Barbara Cannon and Jan Nedergaard, "Nonshivering Thermogenesis and Its Adequate Measurement in Metabolic Studies," Experimental Biology 214 (2011): 242-253, http://dx.doi.org/10.1242/jeb.050989.
Purves, William K., David Sadava, Gordon H. Orians, and H. Craig Heller, "41.7 Endotherms and Ectotherms," in Life: The Science of Biology, 7th ed. (Sunderland: Sinauer Associates, 2003), 788.
Roger Meek, "Reptiles, Thermoregulation, and the Environment," British Chelonia Group, accessed July 9, 2016, http://www.britishcheloniagroup.org.uk/testudo/v4/v4n2thermoreg.
Jonathan A. Akin, "Homeostatic Processes for Thermoregulation," Nature Education Knowledge 3, no. 10 (2011): 7, http://www.nature.com/scitable/knowledge/library/homeostatic-processes-for-thermoregulation-23592046.
David E. Sadava, David M. Hillis, H. Craig Heller, and May Berenbaum, "Physiology, Homeostasis, and Temperature Regulation," in Life: The Science of Biology, 9th ed. (Sunderland: Sinauer Associates, 2009), 839.
John W. Kimball, "The Transport of Heat," Kimball’s Biology Pages, last modified June 25, 2014, http://www.biology-pages.info/H/HeatTransport.html.
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Robert B. Jackson, "Homeostatic Processes for Thermoregulation Involve Form, Function, and Behavior," In Campbell Biology, 10th ed. (San Francisco: Pearson, 2011), 881.
Worthington Biochemical Corporation, "Temperature Effects," Introduction to Enzymes, accessed June 25, 2016, http://www.worthington-biochem.com/introbiochem/tempeffects.html.
Sara M. Hiebert and Jocelyne Noveral, "Are Chicken Embryos Endotherms or Ectotherms? A Laboratory Exercise Integrating Concepts in Thermoregulation and Metabolism," Advances in Physiology Education 31, no. 1 (2007): 97-109, http://dx.doi.org/10.1152/advan.00035.2006.

References

Akin, Jonathan A. "Homeostatic Processes for Thermoregulation." Nature Education Knowledge 3, no. 10 (2011): 7. http://www.nature.com/scitable/knowledge/library/homeostatic-processes-for-thermoregulation-23592046.

Boundless. "Homeostasis: Thermoregulation." Boundless Anatomy and Physiology. Last modified May 26, 2016. https://www.boundless.com/physiology/textbooks/boundless-anatomy-and-physiology-textbook/nutrition-and-metabolism-24/metabolic-rate-and-thermoregulation-234/homeostasis-thermoregulation-1157-11974/.

Brenglemann, G. "Temperature Regulation." In Physiology and Biophysics, edited by T. C. Ruch and H. D. Patton. Vol. III, 105-135. 20th ed. Philadelphia: Saunders, 1973.

Campbell, Kirsten. "How Does Temperature Affect Metabolism?" Accessed June 24, 2016. http://sciencing.com/temperature-affect-metabolism-22581.html

Cannon, Barbara and Jan Nedergaard. "Nonshivering Thermogenesis and Its Adequate Measurement in Metabolic Studies." Experimental Biology 214 (2011): 242-253. http://dx.doi.org/10.1242/jeb.050989.

Castellini, Michael. "Thermoregulation." In Encyclopedia of Marine Mammals, edited by William F. Perrin, Bernd Würsig, and J. G. M. Thewissen, 1166-1170. 2nd ed. Burlington: Academic Press, 2009.

"Convection." Biology-Forums.com. Last modified October 10, 2011. biology-forums.com/definitions/index.php?title=Convection.

Frappell, P. and K. Cummings. "Sources of Heat." In Encyclopedia of Ecology, 1885-1888. Amsterdam: Elsevier, 2008.

Ganong, W. F. "Temperature Regulation." In Review of Medical Physiology, 177-181. 9th ed. Los Altos: Lange Medical Publications, 1979.

Gillam, Paul. "Thermoregulation: A* Understanding for iGCSE Biology." PMG Biology. Last modified February 22, 2015. https://pmgbiology.com/tag/thermoregulation/.

Heindl, Alex L. "Rattlesnakes." Accessed June 24, 2016. http://www.alongtheway.org/rattlesnakes/basics.html.

Hiebert, Sara M. and Jocelyne Noveral. "Are Chicken Embryos Endotherms or Ectotherms? A Laboratory Exercise Integrating Concepts in Thermoregulation and Metabolism." Advances in Physiology Education 31, no. 1 (2007): 97-109. http://dx.doi.org/10.1152/advan.00035.2006.

"Heat Transfer." HyperPhysics. Accessed June 24, 2016. http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatra.html.

Kimball, John W. "The Transport of Heat." Kimball’s Biology Pages. Last modified June 25, 2014. http://www.biology-pages.info/H/HeatTransport.html.

McNab, Brian Keith. "The Impact of Endothermic Hibernation." The Physiological Ecology of Vertebrates: A View From Energetics, 383-385. Ithaca: Comstock Publishing Associates, 2002.

Meek, Roger. "Reptiles, Thermoregulation, and the Environment." British Chelonia Group. Accessed July 9, 2016. http://www.britishcheloniagroup.org.uk/testudo/v4/v4n2thermoreg.

"Mesotherm." Wikipedia. Last modified February 17, 2016. https://en.wikipedia.org/wiki/Mesotherm.

Nishiura, James. "Effect of Temperature on Enzyme Activity." Accessed May 27, 2016. http://academic.brooklyn.cuny.edu/biology/bio4fv/page/enz_act.htm.

OpenStax. "Energy and Heat Balance." OpenStax CNX. Last modified June 19, 2013. http://cnx.org/contents/x9vl-NZc@3/Energy-and-Heat-Balance.

OpenStax. "Homeostasis." OpenStax CNX. Last modified June 26, 2013. https://cnx.org/contents/BP24ZReh@7/Homeostasis.

Oswald, Nick. "Why Do Enzymes Have Optimal Temperatures?" Bitesize Bio. Last modified June 21, 2016. http://bitesizebio.com/120/why-do-enzymes-have-optimal-temperatures/.

Purves, William K., David Sadava, Gordon H. Orians, and H. Craig Heller. "41.7 Endotherms and Ectotherms." In Life: The Science of Biology, 788. 7th ed. Sunderland: Sinauer Associates, 2003.

Raven, Peter H., George B. Johnson, Kenneth A. Mason, Jonathan B. Losos, and Susan R. Singer. "Regulating Body Temperature." In Biology, 877-882. 10th ed., AP ed. New York: McGraw-Hill, 2014.

Reece, Jane B., Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, and Robert B. Jackson. "Homeostatic Processes for Thermoregulation Involve Form, Function, and Behavior." In Campbell Biology, 878-883. 10th ed. San Francisco: Pearson, 2011.

Ricklefs, Robert E. and Gary L. Miller. "Adaptations Match the Temperature Optima of Organisms to the Temperature of the Environment." In Ecology, 86-88. 4th ed. New York: W. H. Freeman and Company, 2000.

Sadava, David E., David M. Hillis, H. Craig Heller, and May Berenbaum. "Physiology, Homeostasis, and Temperature Regulation." In Life: The Science of Biology, 832-848. 9th ed. Sunderland: Sinauer Associates, 2009.

Starr, Cecie and Ralph Taggart. "Heat Gains and Losses." In Biology: The Unity and Diversity of Life, 749. 11th ed. Belmont: Thomson/Brooks-Cole, 2006.

Starr, Cecie and Ralph Taggart. "Temperature Regulation in Mammals." In Biology: The Unity and Diversity of Life, 750-751. 11th ed. Belmont: Thomson/Brooks-Cole, 2006.

"Thermoregulation." Wikipedia. Last modified June 14, 2016. https://en.wikipedia.org/wiki/Thermoregulation.

"Wind Chill." Wikipedia. Last modified March 15, 2016. https://en.wikipedia.org/wiki/Wind_chill.

Worthington Biochemical Corporation. "Temperature Effects." Introduction to Enzymes. Accessed June 25, 2016. http://www.worthington-biochem.com/introbiochem/tempeffects.html.

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MT
Posted 3 years ago. Direct link to MT's post “I have a question Are tu...”
I have a question
Are tuna endotherm or ectotherm? I have ever studied that tuna is Homeotherm in ectotherm. Now I feel confused.
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(4 votes)
Answer
- Nine.Naijai
  Posted 3 years ago. Direct link to Nine.Naijai's post “I found this online. "An...”
  I found this online.
  
  "An endotherm is able to regulate its body
  temperature via metabolic processes, these are commonly known warm blooded animals.
  An ectotherm's body temperature is dictated by the environment surrounding it, the animals are commonly and incorrectly known as cold blooded.
  --
  Poikilotherms are animals that do not require a fixed body temperature, their temperatures can fluctuate with little to no adverse effects to their overall health. Most terrestrial
  ectotherm's are poikilotherms, such as snakes and many lizards, also the naked mole rat is considered to be the only mammal poikilotherm. Homeotherms are animals that maintain a constant body temperature. All endotherms are homeothermic, but some ectotherms, like desert lizards, are so good at maintaining their body temperature with behavioral means that they are
  considered homeothermic."
  
  source: https://faculty.mtsac.edu/trevell/bio2/bio2resources/thermo
  Button navigates to signup page
  (2 votes)
maahtaab
Posted 4 years ago. Direct link to maahtaab's post “I have two questions. Fi...”
I have two questions.
First, is the thermoneutral zone for humans around 24 Celsius or 37?
And second, why do we feel hot when the environment temperature is 37 Celsius, when 37 is the temperature we want our body to have?
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(3 votes)
Answer
- Ivana - Science trainee
  Posted 4 years ago. Direct link to Ivana - Science trainee's post “Thermoneutral zone for hu...”
  Thermoneutral zone for humans is around 24, not 37.
  The thermoneutral zone is defined as the range of ambient temperatures where the body can maintain its core temperature solely through regulating dry heat loss, i.e., skin blood flow.
  
  This paper explains
  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4977175/
  
  Why not 37? Because imagine even if we were nude at that temperature (anything above 30 is too much).
  Also while it is plausible for our basal metabolic rate, not suitable for any kind of work.
  
  Have you noticed that slightest amount of work even at 27 makes you sweat?
  
  We feel hot because we are not static objects which just conduct temperature. We also produce temperature in our core, plus have a skin which is an insulator.
  
  So the reason why you feel hot at 37 is mainly that you have skin whose surface temperature is lower than 37 so your body surface is colder and starts absorbing environmental temperature.
  Comment on Ivana - Science trainee's post “Thermoneutral zone for hu...”
  (3 votes)
Taylor, Vivian
Posted 5 years ago. Direct link to Taylor, Vivian's post “Why would one expect the ...”
Why would one expect the Q10 value of an ectotherm to be around 2?
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(3 votes)
Answer
- Ivana - Science trainee
  Posted 4 years ago. Direct link to Ivana - Science trainee's post “If Q10 is 2 it means an i...”
  If Q10 is 2 it means an increase in the surrounding temperature with an increase in 10 ◦C, and usually resulted in a doubling of the reaction rate.
  
  The Q10 values can be determined from the Arrhenius plots. (In chemical kinetics, an Arrhenius plot displays the logarithm of a reaction rate constant, (, ordinate axis) plotted against reciprocal of the temperature (, abscissa).)
  https://www.google.com/imgres?imgurl=https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2Ff%2Ff6%2FNO2_Arrhenius_k_against_T.svg%2F1200px-NO2_Arrhenius_k_against_T.svg.png&imgrefurl=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FArrhenius_plot&docid=knFyGYn7H893XM&tbnid=k3xTzrdU8e6HCM%3A&vet=10ahUKEwiC3IGzg8blAhUPKlAKHd82DDcQMwhNKAEwAQ..i&w=1200&h=912&bih=625&biw=1366&q=arrhenius%20plots%20for%20temperature&ved=0ahUKEwiC3IGzg8blAhUPKlAKHd82DDcQMwhNKAEwAQ&iact=mrc&uact=8
  
  So I found the paper where Researchers have experimented on Pseudomonas sp. (ectotherm, relying upon external temperature) and phenol degradation was referent variable to detect metabolism of Pseudomonas.
  
  https://www.researchgate.net/publication/322925209_Estimation_of_the_Q10_value_the_Temperature_Coefficient_for_the_Growth_of_Pseudomonas_sp_AQ5-04_on_Phenol
  
  Again, your questions as why is that so?
  And I cannot tell you for sure why the rate usually is 2, it was experimentally obtained and concluded.
  
  Probably it has to do something with Laws of Thermodynamics and logic.
  
  Think about it, if it was 3, 4, or 7, what would it mean in BIological terms?! That metabolism would be super fast, and at 30*C, the organism may just burn out in half an hour. And it does not make sense.
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  (2 votes)
Samuel Lee
Posted 4 years ago. Direct link to Samuel Lee's post “Why would endotherms use ...”
Why would endotherms use more oxygen at lower temperatures and ectotherms use more oxygen at higher temperatures?
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(4 votes)
Answer
- Ivana - Science trainee
  Posted 4 years ago. Direct link to Ivana - Science trainee's post “Because endotherms have f...”
  Because endotherms have fixed body temperature. And that temperature is obviously higher than any environmental unless during hot summers or jumping into Geysers.
  
  The temperature tends to leave body (Law of Thermodynamics) so energy must be used to generate new heat from brown fatty tissue.
  
  Ectotherms need to adapt their body temperatures to the envirnomantal. Let's say they already have 18C body temperature. Thean temperature strats raising. They cannot just 'absorb it from the atmosphere' they have also to generate energy in order to follow the external temperature. Why? because they also have protective layers such as skin, scales, etc. (which might act as isolators).
  
  ONE MORE THING: Work at the higher temperatures require higher energy inputs and you are way easily tired and less likely to do the same amount of work.
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  (0 votes)
Lee Wright
Posted 6 years ago. Direct link to Lee Wright's post “Is the graph also suppose...”
Is the graph also supposed to demonstrate that ectotherms have minimal oxygen consumption regardless of ambient temperature? Or is that just an artifact?
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(3 votes)
Answer
- Ivana - Science trainee
  Posted 4 years ago. Direct link to Ivana - Science trainee's post “Nice observation. No, th...”
  Nice observation.
  
  No, the graph is teaching us that too. Clearly you can distinguish between Ectotherms and Endotherms by the minimally changing curve for Ectotherms.
  
  :D
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  (1 vote)
drunkgraw
Posted 6 years ago. Direct link to drunkgraw's post “Which between a unicellul...”
Which between a unicellular organism, ectotherm and endotherm has the highest BMR and which one is the lowest?
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(2 votes)
Answer
- tyersome
  Posted 6 years ago. Direct link to tyersome's post “This is one of those ques...”
  This is one of those questions that seem reasonable, but are so dependent on the specific organisms that they are probably impossible to get a useful answer for.
  
  For example, unicellular organisms are incredibly diverse (contain organisms from all three domains of life and from multiple eukaryotic kingdoms) — they will not have similar metabolic rates.
  Furthermore, unicellular organisms can't even all be grown at the same temperature — how would you meaningfully compare the metabolic rate of a marine bacterium that lives in arctic waters (prefers 4°C) vs. the rate for an archaebacterium that grows only on a "black smoker " (undersea thermal vent) and prefers 98°C (can grow at up to 122°C):
  https://ocean.si.edu/ecosystems/deep-sea/microbes-keep-hydrothermal-vents-pumping
  
  Another example, is what kind of endotherm — a blue whale? an elephant? a shrew? a hummingbird? an ostrich?
  
  ...
  
  Well, hopefully you found some of that rant interesting or at least mildly entertaining ...
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FrenchHornCat
Posted 6 years ago. Direct link to FrenchHornCat's post “Why do the body temperatu...”
Why do the body temperatures of endotherms vary? Does it involves the percentage of ATP energy which becomes heat, or does it involve the amount of energy different animals have to consume? Or is it unrelated to both of those?
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Answer
- tyersome
  Posted 6 years ago. Direct link to tyersome's post “Here's an article that sh...”
  Here's an article that should help you with this question:
  https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2435.2007.01341.x
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22cgoodwin
Posted 5 years ago. Direct link to 22cgoodwin's post “Why does temperature affe...”
Why does temperature affect the breathing and heart rates of ectothermic organisms?
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Answer
- Ivana - Science trainee
  Posted 4 years ago. Direct link to Ivana - Science trainee's post “Because temperature per s...”
  Because temperature per se affects any kind of work. At higher temperatures, the working machine (or int his case heart) has to work harder and easier gets overheated.
  
  The same way temperature affects Ebdithersm, it also affects Ectitherms, especially because they rely on the temperature. Because temperature directly correlates with metabolism rate.
  
  The greater the temperature faster the metabolism and vice versa.
  
  Here is one interesting paper depicting how also Ectotherms may have energy costs in their metabolisms because sudden increases and decreases impose some kind of stress on bodies. They are physiologically dependant on external temperature and their viability is reduced at extremes.
  
  https://www.sciencedirect.com/science/article/pii/030645659400023C
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maahtaab
Posted 4 years ago. Direct link to maahtaab's post “Is the the temperature in...”
Is the the temperature in thermoneutral zone, the temperature we use when calculating BMR?
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Answer
- Ivana - Science trainee
  Posted 4 years ago. Direct link to Ivana - Science trainee's post “In the previous article i...”
  In the previous article it is stated - For an endotherm, the BMR is also measured when the animal is in a thermoneutral environment, that is, one where the organism does not expend extra energy (above baseline) to maintain temperature.
  
  So yes, my answer is yes.
  
  And again to define thermoneutral temperature - The thermoneutral zone (TNZ) is defined as the range of ambient temperatures without regulatory changes in metabolic heat production or evaporative heat loss.
  
  https://www.bioscience.org/2012/v4e/af/518/fulltext.htm
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Cameron siler
Posted 3 years ago. Direct link to Cameron siler's post “Do endotherms respirate f...”
Do endotherms respirate faster than ectotherms?
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