What are the reactants of enzyme-catalyzed reactions called?

substrates.

Explanation:

Substrates bind to a part of an enzyme called the active site and remain bound to the enzyme until the reaction is complete, when the products are released. Temperature, pH, and regulatory molecules can affect the activity of enzymes.

answer: that would be cheating

explanation:

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.