Ectothermy- The Efficient Approach to life Flashcards
Give a brief description of Shelford’s Law of Tolerance.
- In order for an organism to succeed in a given environment, each of a complex set of conditions must remain in the tolerance range of that organism and if any one condition exceeds the maximum or minimum tolerance of that organism, it will fail to thrive.
- This space is defined by the diverse requirements and is termed the organisms niche.`
Why are biochemical activities sensitive to temperature?
- Biochemical activities are sensitive to temperature because enzymes have an optimum.
- Temperature restrictions on animals are due to their need to maintain biochemical activity.
- Cold Temp= metabolic activities are too slow to maintain activity and reproduction
- High Temp= Enzyme activity is impaired or destroyed
What temperature range to animals generally function at?
- 0-40 Degrees Celsius. Animals may locate such habitats or develop the means to stabilize their metabolism
Why are “cold-blooded” and “warm- blooded” inaccurate descriptions?
They are not well defined states as they suggest one is slow and sluggish and the other is quick and active?
What do Poikilothermic and Homoeothermic mean?
- Poikilothermic: Variable body temperature
- Homoeothermic: Maintains a constant body temperature
- All animals produce heat from cellular metabolism
Briefly describe how an ectotherm would maintain their body temperature
- Their heat is conducted away as fast as it is produced so they may behaviourally select areas of more favourable temperature, such as basking in the sun.
What further challenges do marine/freshwater ectotherms have to cope with?
- Terrestrial ecto/endotherms tend to have a body temperature ranging from 30-40 Degrees C.
- Marine/freshwater ectotherms have to deal with waters fluctuating temperatures. Water has an extremely high capability to trap and conduct heat compared to air.
- Pure water freezes at 0 C. Increasing the osmolar concentration drops this value which results in water of approx -2 in the artic during winter.
What is Q10?
- Q10 can be linked to Ea, it can also depend on the temperature interval considered.
- Q10 of a reaction or process is the change in rate observed or extrapolated for a 10 Degree (K or C) rise in temperature.
What makes Trematomus so successful in the Antartic?
- Body fluid maintained at -0.8 Degrees C
- Temperature independance
Describe the four different methods of heat transfer.
- Thermal Radiation: energy travels from place to place via electromagnetic waves (so do not need physical contact). It is a potential source of heat loss and heat gain. Surface colour can be important for absorbing radiation.
- Convection: flow of heat by the mass movement of an intervening fluid (gas or liquid). Boundary layers can be important. “Natural” (heat rises) and “forced” convection (e.g. circulation, wind etc)
- Conduction: direct flow of heat between bodies in contact
- Latent heat of evaporation: turning liquid into vapour takes addition energy so evaporation of sweat removes heat.
Ectotherms rely on different mechanisms of heat transfer. Explain how we know they do not rely on conduction alone.
Dead ectotherms heat and cool by conduction alone, while the difference between rates of heating and cooling in live lizards is fully explained by the differences in heart rate and the resultant different rates of convection by blood flow.
How could an ectotherm use metabolic adjustments to maintain temperature?
- Within limits, most ectotherms can adjust metabolic rate to the prevailing temperature.
- Temperature regulation involves complex biochemical and cellular adjustments.
- Allows a fish or salamander to sustain the same level of activity in warm or cold water.
- Ectothermy comes at a cost of flexibility but at a clear benefit of efficiency.
