The decomposition of slaked lime, Ca(OH)2(s), into lime,

September 19, 2016 Animal form and function; the interaction of the body with the external environment Concepts 40. 1-3 Organisms have to exchange energy and materials with the environment ● Food, waste, gases, energy ● Materials must be dissolved in aqueous solution to move across a membrane ● Single cellular and diploblastic organism use diffusion ● Flatworms can get most of their needs from diffusion ; the rest is diffused from the gastrovascular cavity High surface area to volume ration ● Pro ○ Good diffusion ○ Less needed for efficient distribution systems ● Cons ○ More difficult to control gain and loss ○ Limits complexities More complex animals ● Advantages for function and versatility in different conditions ● Need more than body surface area for contact with environment ○ Lungs ● Exchange surfaces are highly branched or folded, often internal ● Cells have to be surrounded by fluid Internal exchange surfaces allow regulation of water loss ● Waterproof body covering reduces loss to evaporation ● Control of exposure to the environment ● Humid enclosure decrease evaporation rate Strategies for dealing with variations in the external environments ● Regulators ○ Limits internal change with internal mechanisms ● Conformers ○ Allow internal conditions change with external environment Homeostasis is a relatively const