What must energy be converted to in order to be used by muscles and other cells?

Muscles and other cells require energy in the form of Adenosine Triphosphate (ATP) to perform work. ATP is often referred to as the energy currency of the cell because it provides the necessary energy for various biological processes, including muscle contraction, biosynthesis, and active transport.

When energy from nutrients such as carbohydrates and fats is metabolized, it is ultimately used to generate ATP. This process involves breakdown pathways such as glycolysis and the citric acid cycle, where the stored energy in glucose and fatty acids is harnessed to form ATP. Once ATP is produced, it can be readily used by the cells’ mechanisms for immediate energy needs.

Other options provided, such as glucose, lactate, and creatine phosphate, serve different roles in energy metabolism. Glucose is a primary energy source that must first be converted through metabolic pathways to generate ATP, while lactate is a byproduct of anaerobic metabolism that can be recycled into glucose but cannot be directly used as energy by cells. Creatine phosphate can help regenerate ATP during short bursts of intense activity but is not directly utilized as energy by cells in the same manner as ATP. Thus, the crucial role ATP plays as the direct source of energy for muscle contractions and cellular functions makes