Match the descriptions below with their corresponding terms.
1. A process that involves the transfer of a phosphate group from a substrate molecule to ADP, forming ATP.
2. The process where electrons are transferred from NADH or FADH2 to O2 through a series of electron carriers.
3. The breakdown of carbohydrates into simpler compounds starting with glycolysis.
4. This happens when all active sites on an enzyme are occupied by substrate molecules.
A. Oxidative phosphorylation
B. Substrate-level phosphorylation
C. Carbohydrate catabolism
D. Saturation