What is the primary source of energy used by the body for all metabolic processes?

The primary source of energy used by the body for all metabolic processes is glucose. Glucose is a simple sugar that is readily absorbed into the bloodstream after the digestion of carbohydrates. It is then transported to cells throughout the body where it can be utilized to produce adenosine triphosphate (ATP), the molecule that serves as the primary energy currency of the cell.

During cellular respiration, glucose undergoes a series of biochemical reactions that convert its energy into ATP, which is then used for various cellular activities, including muscle contraction, nerve impulse transmission, and biosynthesis of biomolecules. The body's preference for glucose as an energy source is crucial, especially in the brain and red blood cells, which rely heavily on glucose for their energy demands.

Fats, while also a significant energy source and more energy-dense than carbohydrates, are typically utilized during prolonged periods of exercise or fasting. Ribose is a sugar that is part of the structural framework of ATP, but it is not the primary energy source the body uses; it is involved in the synthesis and regeneration of ATP. Cellulose is a polysaccharide that serves primarily as dietary fiber in humans and is not digested for energy.

Therefore, glucose is essential for immediate energy needs, making