Match the following terms and definitions. 1. assimilation occurring in the absence of oxygen 2. cellular respiration process that involves the third step in the chemical breakdown of glucose; transferring electrons to form ATP 3. Krebs cycle process that involves the second step in the chemical breakdown of glucose; converting pyruvic acid into carbon dioxide 4. electron transport chain occurring in the presence of oxygen 5. aerobic cell activities associated with the utilization of food molecules and energy in life processes 6. anaerobic a series of chemical reactions that break down sugars and produce energy