How do enzymes speed up chemical reactions?

They lower the activation energies of reactions.

They react with substrates to form new compounds.

They raise the activation energies of reactions.

They react with products to form new compounds.

-They lower the activation energies of reactions.

Explanation:

Enzymes can be defined as biocatalysts that enhances rate of reactions, without being changing themselves in overall process.

They show enormous catalytic power and increase reaction rate by decreasing the activation energy required for the reaction. The energy required to lower the activation energy comes from the binding energy, released due to the interactions between substrate and enzyme.

Thus, the correct answer is 'first option.'