Answer:
1. Reactants to products
2. Catalyst
3. Activation energy
4. Enzymes
Step-by-step explanation:
Chemical reactions involve the formation of substances called PRODUCTS from other substances called REACTANTS. The addition of certain substances called CATALYSTS to chemical reactions occuring outside living environment helps to spedeen up the chemical reaction by LOWERING ITS ACTIVATION ENERGY, which is the energy required to start the reaction.
However, within a living environment, molecules which act as catalyst called ENZYMES perform the same function of making reaction to proceed very quickly. Please find the answers to the omitted spaces in BOLD.
Chemical reactions convert [REACTANTS] to [PRODUCTS]. In nonliving systems, the presence of a(n) [CATALYST] allows the reaction to proceed very quickly and have a lower [ACTIVATION ENERGY]. In living systems, this function is carried out by proteins calledH [ENZYMES].