Question

which statement best explains how enzymes speed up chemical reactions?
o enzymes provide heat to chemical reactions.
o enzymes increase the concentration of the reactants.
o enzymes increase the distance between reactant molecules.
o enzymes lower the activation energy of a reaction.

Explanation:

Enzymes are biological catalysts. They work by reducing the activation - energy barrier that reactants must overcome to form products. Activation energy is the minimum amount of energy required for a chemical reaction to occur. Lowering it allows the reaction to proceed more quickly. Enzymes do not provide heat, increase reactant concentration, or increase the distance between reactant molecules to speed up reactions.

Answer:

Enzymes lower the activation energy of a reaction.