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15.2 Thermoregulation In Ectotherms:
Terms in this set (31)
What is a feature of enzymes?
The enzymes controlling the rates of chemical reactions needed for life are very temperature sensitive. Each enzyme has an optimum temperature at which it works most efficiently. If the temperature gets too high, the enzyme becomes denatured.
As a result of this temperature sensitivity, what is an important aspect of homeostasis in animals?
An important aspect of homeostasis in many animals is the maintenance of a relatively constant core body temperature in order to maintain optimum enzyme activity.
What is this maintenance of a relativity constant core body temperature called?
This process of maintaining a relatively constant core body temperature is called thermoregulation.
What happens to organisms' temperatures?
Organisms are constantly heating up and cooling down as a result of their surroundings.
What do these changes in temperature depend on?
These changes depend on a number of physical process
What are some examples of physical processes which can affect the organisms temperature?
Exothermic chemical reactions, Latent heat of evaporation, Radiation, Convection and Conduction
What is the latent heat of evaporation?
Objects cool down as water evaporates from a surface
What is radiation?
Radiation is the transmission of electromagnetic waves to and from the air, water or ground
What is convection?
Convection is the heating and cooling by currents of air or water, warm water rises and cooler air or water sinks setting up convection currents in an organism
What is conduction?
Conduction is heating up as a result of the collision of molecules. Air is not a good conductor of heat but the ground and water are
What determines the core temperature of an organism?
In many cases, the balance between heating and cooling determines the core temperature of an organism
What can animals be considered as?
Animals can be considered as ectotherms or endotherms depending on how they maintain and control their body temperature
Are most animals ectotherms or endotherms?
Most animals are ectotherms and use their surroundings to warm their bodies. Ectotherm literally means outside heat.
What are ectotherms core temperature dependent on?
Ectotherms core body temperature is heavily dependent on their environment.
Give examples of organisms that are ectotherms
Ectotherms include all the invertebrate animals, along with fish, amphibians and reptiles
What is special about ectotherms that live in water?
Many ectotherms living in water do not need to thermoregulate. The high heat capacity of their environment does not change that much
What is the issue with ectotherms living on land?
Ectotherms that live on land have much bigger issues with temperature regulation. The temperature of the air can vary dramatically both between seasons and even over a 24 hour period from the middle of the day to the end.
What type of animals are endotherms?
Mammals and birds are endotherms
What are endotherms?
Endotherms are organisms that depend on their metabolic processes to warm them up and they usually maintain a very stable core temperature regardless of the environment. Endotherm literally means inside heat
What is special about endotherms?
Endotherms have adaptations which enable them to maintain their body temperature and to take advantage of warmth from the environment. As a result endotherms survive in a wide range of environments
Compare endotherms and ectotherms
Keeping warm in cold conditions and cooling down in hot conditions are both active processes. The metabolic rate of endotherms is around five times higher than ectotherms, so they need to consume more food to meet their metabolic needs than ectotherms of a similar size.
What can ectotherms not do which endotherms can?
Ectotherms cannot control their body temperature using their metabolism, however they have evolved a range of behavioural responses that enable them to overcome the limitations imposed by the temperature of their surroundings.
Why might an ectotherm have to warm up?
Sometimes ectotherms need warm up to reach a temperature at which theri metabolic reactions happen fast enough for them to be active
Give some examples of how ectotherms might warm themselves up
They may bask in the sun, by orienting their bodies so that the maximum surface area is exposed to the sun, or even extend their body to increase the surface area to the sun. Ectotherms can increase their body temperature through conduction by pressing their bodies against the warm ground. They also get warmer as a result of exothermic metabolic reactions
Why do ectotherms need to cool down sometimes?
Ectotherms sometimes need to cool down to prevent their core temperature reaching a point where enzymes begin to denature
Give some examples of how ectotherms may cool down
Ectotherms shelter from the sun by seeking shade, hiding in cracks, or even digging burrows or Ectotherms may press their bodies against cool, shady earth stones or move into available mud or water orEctotherms may orientate their bodies so that the minimum surface area is exposed to the sun and minimise their movements to reduce the metabolic heat generated.
Besides behavioural responses to the external heat, what else do ectotherms have?
Much of the thermoregulation by ectotherms is the result of behavioral responses, but some of them have physiological responses to.
Give an example
Dark colours absorb more radiation compared to light colours. Lizards living in colder climates tend to be darker coloured then lizards living in hotter countries so that they get warmer
What is another example of an ectotherm physiological response?
Some ectotherms also alter their heart rate to increase or decrease the metabolic rate and some items to affect the warming or cooling across the body surfaces
What do these behavioural and physiological adaptations allow for?
Ectotherms are always more vulnerable to fluctuations in the environment than endotherms However, by using a number of behavioural and physiological strategies, many of them can maintain relatively stable core temperatures. They need less food than endotherms as they use less energy regulating their temperature and so they can survive in some very difficult habitats where food is sacre
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