Which simple sugar is considered an important source of energy?

Glucose is widely recognized as a primary source of energy for the body's cells. It is a monosaccharide, which means it is one of the simplest forms of carbohydrates, making it easily absorbable in the bloodstream. Once ingested, glucose can be rapidly utilized by the body to generate adenosine triphosphate (ATP), the molecule that stores and transfers energy in cells.

Additionally, glucose plays a crucial role in cellular respiration, a process where cells convert glucose and oxygen into energy, carbon dioxide, and water. This process is vital for maintaining the body's energy balance and supporting various physiological functions.

While fructose, sucrose, and lactose are types of sugars, they either require additional steps to be converted into glucose or are not as directly utilized by the body for energy. For instance, fructose is metabolized differently and does not elevate blood sugar levels as efficiently as glucose does. Sucrose is a disaccharide that must be broken down into glucose and fructose before it can be used for energy, and lactose requires the enzyme lactase for digestion. Thus, glucose stands out as the most direct and efficient energy source among the choices listed.