The body obtains vitamin A in two ways. One is by manufacturing it from carotene, a vitamin precursor found in such vegetables as carrots, broccoli, squash, spinach, kale, and sweet potatoes.The other is by absorbing ready-made vitamin A from plant-eating organisms.he body obtains vitamin A in two ways. One is by manufacturing it from carotene, a vitamin precursor found in such vegetables as carrots, broccoli, squash, spinach, kale, and sweet potatoes.
A catalyst is like adding a bit of magic to a chemical reaction. Reactions need a certain amount of energy in order to happen. If they don't have it, oh well, the reaction probably can't happen. A catalyst lowers the amount of energy needed so that a reaction can happen more easily. A catalyst is all about energy.
An enzyme is a catalyst; it has all the parts for the reaction on it and help organic materials break down or transfer energy or whatever reaction it needs. Catalysts (including enzymes) work by lowering the activation energy of a reaction so that more reactants can be converted to products. They are not used up themselves in the reaction and do not affect the equilibrium. They only speed up the rate at which equilibrium is achieved.