How is corrosion different from rusting?

Corrosion is when over time a substance begins to break down, and can even break down to the atomic level. Rusting is a chemical process when a substance includes iron. In the presence of oxygen and/or water, the iron turns into iron oxide which produces this reddish-brown color.

Explanation:

Metabollic rate is the amount of energy expended from an organism at a given point in time.

Equation of how glucose (food) is broken down via respiration:

C6H12O6(s) + 6O2(g) --> 6H2O(l) + 6CO2(g)

The amount of energy produced for the types of food is roughly proportional to the amount of oxygen use, so that the metabolic rate can be measured by measuring the rate of oxygen consumption.