Humans get there energy primarily from glucose I believe. We break down glucose to get ATP (Adenosine Triphosphate) which is then used to supply energy to our cells in order to function.
cells came from nonliving things.
The efficiency indicates the manner in which the inputs are used by the system. Being efficient means the system uses inputs in a `right' way. If the input-output ratio is adverse, we say that the system is inefficient though it produces the desired output.
