The reaction of an acid with a base, for example, results in the creation of a salt and water. Some, but not all, reactions can be reversed. See nuclear reaction. An action that results directly from or counteracts another action, especially the change in a body's motion as a result of a force applied to it.
Snakes are cold-blooded creatures, just like amphibians. When a certain animal is cold-blooded, it basically means that they are able to adapt their own internal temperature to that of their environment. When a snake is in a cool environment, their body temperature tends to drop rather quickly.
A snake of any given weight eats far less than does a mammal of the same size because snakes are cold-blooded. A mammal must eat more in order to generate enough energy to maintain its body temperature. A snake only uses about 10 percent of the amount of energy used by a mammal of similar size.