16. Identify each of the following molecules as reactants or products of the Krebs cycle: Acetyl COA
Carbon dioxide
NADH
NAD+
FAD
ATP
FADH

i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme