What are the main products of the Krebs cycle?

The Krebs cycle, also known as the citric acid cycle or tricarboxylic acid (TCA) cycle, primarily produces several key molecules that are essential for cellular respiration and energy production. Among these products, ATP (adenosine triphosphate) serves as the main energy currency of the cell, while CO2 (carbon dioxide) is a waste product that is expelled from the cell and eventually exhaled by organisms.

Additionally, the Krebs cycle generates NADH (nicotinamide adenine dinucleotide in its reduced form) and FADH2 (flavin adenine dinucleotide in its reduced form), both of which are crucial electron carriers. These molecules play a significant role in the electron transport chain, where they facilitate the production of more ATP through oxidative phosphorylation.

The other options include products that are not direct outcomes of the Krebs cycle or are simply not part of its primary outputs, such as glucose and lactic acid, which relate to different metabolic pathways. Thus, the main products of the Krebs cycle are indeed ATP, CO2, NADH, and FADH2, confirming that the choice indicating these four substances is accurate.