The repressible and inducible operons are both types of negative gene regulation. The trp operon (repressible) works so that when trp is present, it binds with an inactive repressor to activate it, and therefore the operon turns off so it can inhibit its own production. The lac operon (inducible) works so that if lac is present it binds with the active repressor to turn it inactive, and turn the gene that codes for an enzymes that aid in lactose metabolization off.
Animals maintain a constant internal body temperature even when the external temperatures are fluctuating. Animals do this by cooling themselves down when the external temperature is too warm for their internal process to occur normally, and warming themselves up when it is too cold. Animals can regulate their internal temperature using processes such as maintenance of metabolism, sweating, and goosebumps.