Biology 2601A/B Lecture : organismal phys
20 Feb 2012
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Document Summary
Insects have to deal with the variability of temperatures over the course of winter. Endotherms deal with the cold by increasing their metabolic rate to maintain a constant body temperature. The temperature of ectotherms, however, is affect by the environment. Endotherms/homeotherms defend a constant body temperature by producing heat, insulation, and counter-current heat exchange devices. Ectotherms deal with low temperatures by migration (avoid low temperatures altogether) and bees expend more energy to heat hive. Some can t migrate and expend energy like this, so they have to put up with these low temperatures. Life below 0 c is bad because organisms are mostly water and they can freeze solid. When it s cold, water becomes solid and becomes less dense (it expands). Small quantities of water can supercool to -20 c (insects tend to be small). Freezing will be induced in the presence of a nucleus (like ice).
