Exercise 1 Answer these questions 1. Is what a enzyme? Which two kinds is the enzyme divided into basing on its constitute? 2. How is a enzyme divided into a group? 3. What is The characteristics of a enz yme reaction? What is the enzyme center?Exercise 1： ◼ Answer these questions? ◼ 1.Is what a enzyme? Which two kinds is the enzyme divided into basing on its constitute? ◼ 2.How is a enzyme divided into a group? ◼ 3.What is The characteristics of a enzyme reaction? What is the enzyme center?