Which term describes an anaerobic reaction in which glucose is only partially broken down to release energy?

• A. Lactic acid fermentation
• B. Chemosynthesis
• C. Fermentation
• D. Point mutations

Answer: (C)

In anaerobic conditions, energy from glucose comes from fermentation, a process that partially breaks down glucose to release a small amount of ATP. When oxygen isn’t available, cells can’t fully oxidize glucose through the full aerobic respiration pathway, so glycolysis keeps running and NAD+ must be regenerated to keep glycolysis going. Fermentation accomplishes this by converting the end product of glycolysis (pyruvate) into substances like lactic acid or ethanol, depending on the organism. This allows some ATP to be produced without oxygen, but far less than in aerobic respiration.

Lactic acid fermentation is a specific type of fermentation that produces lactic acid, so it’s not the general term the question is asking for. Chemosynthesis is a different process where organisms obtain energy from inorganic molecules, not from partially breaking down glucose. Point mutations are changes in DNA, not metabolic energy processes.