Which molecule serves as the primary energy currency produced from sugars?

• A. ATP
• B. ADP
• C. NADH
• D. FADH2

Answer: (A)

ATP is the molecule that serves as the cell’s energy currency. As sugars like glucose are metabolized through glycolysis and the subsequent steps of cellular respiration, energy from the broken bonds is captured in the form of ATP via substrate-level phosphorylation and, more abundantly, oxidative phosphorylation. This ATP is then used directly to power cellular tasks such as muscle contraction, transport of molecules across membranes, and biosynthetic reactions. In contrast, ADP is what ATP becomes after donating a phosphate to release energy, and NADH and FADH2 are electron carriers that shuttle energy to the mitochondria to drive ATP production, rather than being the direct energy currency themselves. So, ATP is the primary energy currency produced from sugars.