The glycolytic (lactic acid) system is characterized by which statement?

• A. Derived from glucose in the bloodstream, producing about 2 ATP
• B. Requires oxygen for energy production
• C. It occurs exclusively in mitochondria
• D. Uses fatty acids as substrate

Answer: (A)

Glycolysis is the fast, anaerobic energy pathway that happens in the cell’s cytosol. It starts with glucose and yields a net of about 2 ATP per glucose molecule, with lactate produced when oxygen availability is limited. This system does not require oxygen, does not occur in mitochondria, and does not use fatty acids as its primary substrate. The statement that glucose from the bloodstream can lead to about 2 ATP fits these features, making it the best description of the glycolytic (lactic acid) system.