Which statement about enzymes is true?
a. an enzyme functions to increase the rate of a chemical reaction. b. enzymes are proteins that function as catalysts in nonliving things. c. each enzyme can catalyze many different biochemical reactions. d. enzymes and substrates fit together like a lock and key.

The correct answer is A) An enzyme functions to increase the rate of a chemical reaction.

Enzymes are the substances produced by living organisms and they speed up the chemical reactions occurring in the body. They are mainly protein molecules and by increasing the rate of reaction in the living system, they act as catalyst.

Every enzyme is very specific for its function as it catalyzes a specific reaction.

For example- Pepsin in the stomach helps in the digestion of proteins only.

In an old model of lock and key, enzymes and substrates fit together but it has now been replaced by a new model called Induced fit.

Thus, A) is the right answer.

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