biological catalysts:  The molecules.that can speed up the chemical reactions in cells is called a biological catalyst.
enzyms as biological catalyst : enzyms are soluble protein molecules.they can speed up the chemical reactions in cells respiration,photosynthesis and making new protiens are include in this reaction. due to this reaction enzymes are some times called as biological catalyst.
                         In enzime catalized reaction, the substract is changed to the product via a high energy transition in the state. this state has a very short life cycle and it is stabilized by the enzyme
                                       An example of this type of reaction is decomposition of hydrogen peroxide into water and oxygen. Although the reaction is strongly favored thermodynamically, it is very slow unless catalyzed