Question

which of the following statements about enzymes is not true?
enzymes work best at a specified ph.
enzymes raise the amount of energy needed for a chemical reaction
enzymes are proteins.
the shape of an enzyme allows it to do its job.

Explanation:

Enzymes are biological catalysts. They are proteins (so "Enzymes are proteins" is true). Their shape is crucial for their function (as they bind to specific substrates, so "The shape of an enzyme allows it to do its job" is true). Enzymes work best at a specific pH (and temperature, so "Enzymes work best at a specified pH" is true). Enzymes lower the activation energy (the amount of energy needed for a chemical reaction), not raise it.

Answer:

Enzymes raise the amount of energy needed for a chemical reaction.