19. An acid has a sour taste, can react with many metals and is defined as a substance that releases hydrogen ions in detectable amounts. Acids are also defined as proton donors. Bases have a bitter taste, feel slippery and are proton acceptors. They take up hydrogen ions in a detectable amount. The concept of pH is basically a system devised to assist in detecting how acidic or how basic a given substance is.
20. The general mechanism of enzyme activity is that every chemical reaction requires activation energy to be absorbed into the reaction. There are three basic steps to be involved in the mechanism of enzyme actions. The first is the enzymes active sites must first bind with the substrates on which it acts. The second is the enzyme substrate complex undergoes internal rearrangements that form the product and the third is the enzyme releases the product of the reaction.