What is the main output of cellular respiration?

The main output of cellular respiration is adenosine triphosphate (ATP). ATP is often referred to as the energy currency of the cell, as it is the primary molecule used to store and transfer energy within cells. Cellular respiration includes several stages: glycolysis, the Krebs cycle, and oxidative phosphorylation, all of which work together to convert the chemical energy in glucose into ATP.

While carbon dioxide and water are produced as byproducts of the process, the goal of cellular respiration is to produce ATP from the energy stored in glucose. This process is essential for cells to perform biological functions, as ATP provides the energy needed for various cellular activities, including muscle contraction, nerve impulse propagation, and biosynthetic reactions.

The choices that mention glucose and oxygen or nucleotides and proteins do not accurately represent the primary purpose or output of cellular respiration, which is focused on generating ATP. Thus, the correct identification of ATP as the main output highlights its critical role in energy transfer within biological systems.