You might see the word alloy described as a mixture of metals, but that's a little bit misleading because some alloys contain only one metal and it's mixed in with other substances that are nonmetals (cast iron, for example, is an alloy made of just one metal, iron, mixed with one nonmetal, carbon).
Energy substrates in the human body are either carbohydrates, fat or proteins. Protein degradation yields amino acid residues which can be converted to carbohydrates and used in energy production. Carbohydrates (sugars) and amino acids from proteins give approximately 4 kcal/gram dry weight when burned in the body.
In chemistry, a substrate is typically the chemical species being observed in a chemical reaction, which reacts with reagent to generate a product.n biochemistry, an enzyme substrate is the material upon which an enzyme acts. When referring to Le Chatelier's Principle, the substrate is the reagent whose concentration is changed. The term substrate is highly context-dependent.