Answer:
Metabolism - the chemical process within a living organism in order to maintain life
Explanation:
The common use it 'my metabolism is really slow/fast', usually heard in fitness and diet communities. The biggest difference is that, while metabolism does deal with the burning of energy from food, it really covers the processes using all materials such as water, food, nutrients, and oxygen in the cells to produce the body's energy.
The presence of the receptor in a cell for a particular hormone decide whether the cell is able to respond to a hormone. Cells which do not have a receptor are not directly influenced by hormone.
The answer should be proteins. Because the protein is consists of different kinds of amino acids(usually 20 in total). And our cell can not produce essential amino acids itself.
