AP BIOLOGY

Detailed explanation-1: -After citric acid forms, it goes through a series of reactions that release energy. The energy is captured in molecules of NADH, ATP, and FADH2, another energy-carrying compound. Carbon dioxide is also released as a waste product of these reactions.

Detailed explanation-2: -The waste product of the Krebs cycle is carbon dioxide (CO2). During the series of reactions of the Krebs cycle, carbon atoms (C) combine with oxygen (O2) to form carbon dioxide (CO2). This carbon dioxide is eliminated from the body through the lungs as a person exhales.

Detailed explanation-3: -Carbon dioxide is an important side product of both glycolysis and the citric acid cycle (Krebs cycle). This oxidized carbon represents an end product of metabolism that, ultimately, needs to be removed using transport to the lungs and subsequent expiration out into the surrounding environment.