Question 26

Proteins include enzymes.

Enzymes are biological catalysts that facilitate biochemical reactions, and they are classified under proteins. This means that proteins play a crucial role in various biological processes, including metabolism.

A) Carbohydrates

Carbohydrates are a class of biological molecules primarily used for energy storage and structural support in cells. They do not function as enzymes, which are specific to proteins that catalyze biochemical reactions.

B) Vitamins

Vitamins are organic compounds that are essential for various metabolic processes in the body, but they are not enzymes themselves. While some vitamins may act as coenzymes, they do not belong to the class of molecules that includes enzymes.

C) Lipids

Lipids are a class of biological molecules that include fats, oils, and phospholipids, primarily serving roles in energy storage and cellular structure. They do not include enzymes, which are specifically a function of proteins.

D) Proteins

Proteins are the class of biological molecules that includes enzymes. Enzymes are specialized proteins that catalyze reactions by lowering the activation energy needed for those reactions to proceed, making them vital for various biological functions.

Conclusion

Proteins are definitively the class of molecules that includes enzymes, as enzymes are specialized proteins that facilitate biochemical reactions. Other options, such as carbohydrates, vitamins, and lipids, do not serve this catalytic role and are thus not classified as enzymes. Therefore, D is the only correct answer among the choices provided.