Final answer:
Anaerobic respiration and fermentation both occur without oxygen but differ in their use of the electron transport chain and their final electron acceptor. Fermentation results in organic byproducts like lactic acid or ethanol, while anaerobic respiration transfers electrons to inorganic molecules. The metabolic pathways organisms use depend on their enzyme capabilities and oxygen requirements.
Step-by-step explanation:
Comparison Between Fermentation, Anaerobic, and Aerobic Respiration
The principal difference between anaerobic respiration and fermentation is their final electron acceptor. Anaerobic respiration uses glycolysis, the TCA cycle, and the electron transport chain (ETC) but eventually transfers electrons to an inorganic molecule. On the other hand, fermentation also starts with glycolysis but does not utilize the TCA cycle or ETC; instead, it ends with the transfer of electrons to an organic molecule, commonly resulting in lactic acid or ethanol.
Fermentation allows organisms to generate ATP without oxygen, though less efficiently than with aerobic respiration, which requires oxygen to produce ATP through the full cellular respiration pathway including the TCA cycle and ETC. Entities that undergo fermentation, such as some bacteria, fungi, and animal cells, can do so in both the presence and absence of oxygen, although the yield of ATP is significantly lower than when oxygen is present and aerobic respiration can proceed.
Determining whether a bacterium utilizes aerobic respiration, anaerobic respiration, or fermentation depends on the presence of specific enzymes indicative of these pathways and the test results indicating their metabolic processes. These bacteria can often be categorized as obligate anaerobes, facultative anaerobes, or aerobes based on their oxygen requirements and metabolic capabilities.