Final answer:
Carbohydrates serve as a structural component, provide an energy source, and help as an identifier of cell types. They do not d) act as catalysts of chemical reactions.
Step-by-step explanation:
Carbohydrates serve several functions in cells and organisms. They act as a structural component of cells and organisms, providing support and protection.
Carbohydrates also provide an energy source for cells, as they can be broken down into glucose, which is then converted into ATP, the primary fuel molecule for cells.
Additionally, carbohydrates can act as identifiers of cell types, helping cells recognize and communicate with each other. However, carbohydrates do not act as catalysts of chemical reactions.