Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

Which process is less efficient because it does not use oxygen?

1. Aerobic Respiration

2. Fermentation

3. Cellular Respiration

4. Photosynthesis

The correct answer is: Fermentation

Fermentation is a process that occurs in the absence of oxygen, making it less efficient for energy production compared to aerobic respiration. In aerobic respiration, organisms use oxygen to break down glucose, which yields a significantly higher amount of ATP (adenosine triphosphate), the energy currency of cells. Typically, aerobic respiration produces around 36 to 38 ATP molecules per glucose molecule. In contrast, fermentation can only produce a maximum of 2 ATP molecules per glucose molecule. This marked difference in ATP yield illustrates why fermentation is deemed less efficient. While fermentation enables certain organisms to survive and produce energy in anaerobic conditions, it is not optimal for energy production, which is why certain cells prefer aerobic pathways when oxygen is present to maximize energy output. Photosynthesis, although it involves energy transformation in plants, and cellular respiration, which can occur with or without oxygen but is generally more efficient in aerobic conditions, do not directly relate to the efficiency of energy production without oxygen. Therefore, fermentation stands out as the correct answer to this question.