Which biomolecule is considered the primary energy source for the body's cells?

Glucose is considered the primary energy source for the body's cells because it is a simple sugar that is easily metabolized to provide immediate energy. When carbohydrates are ingested, they are broken down into glucose, which enters the bloodstream and can be taken up by cells. Once inside the cells, glucose undergoes processes such as glycolysis and the citric acid cycle, ultimately leading to the production of ATP (adenosine triphosphate), the molecule that stores and transfers energy within cells.

The body relies heavily on glucose for energy, especially during high-intensity exercises and other activities that require quick bursts of energy. While fats and proteins can also serve as energy sources, they are typically utilized under different metabolic conditions or when glucose levels are low. Fats provide a more sustained energy supply but require more oxygen to metabolize, thus making glucose the preferred source for immediate energy needs. Vitamins play essential roles in various biochemical processes but do not directly supply energy to cells.