Questions: Which of the following classes of biological molecules includes enzymes? Carbohydrates Proteins Lipids Vitamins

The answer is the second one (Proteins): Proteins.

Explanation for each option:

1. Carbohydrates: Incorrect. Carbohydrates are primarily involved in energy storage and structural functions, not in catalyzing biochemical reactions.
2. Proteins: Correct. Enzymes are a type of protein that act as catalysts to speed up biochemical reactions in living organisms.
3. Lipids: Incorrect. Lipids are involved in energy storage, cell membrane structure, and signaling, but they do not function as enzymes.
4. Vitamins: Incorrect. Vitamins are organic molecules that often serve as coenzymes or cofactors in enzymatic reactions, but they are not enzymes themselves.

Summary: Enzymes are included in the class of biological molecules known as proteins.