Question

Why do organisms undergo fermentation in the absence of oxygen?

Answer 1

Organisms undergo fermentation in the absence of oxygen as an alternative to aerobic respiration to generate ATP. It involves the breakdown of glucose without the use of oxygen and produces a smaller amount of ATP. Examples include alcoholic fermentation and lactic acid fermentation.

Step-by-step explanation:

In the absence of oxygen, organisms undergo fermentation as an alternative to aerobic respiration to generate ATP. Fermentation is a metabolic process that occurs in the cytoplasm of cells and involves the breakdown of glucose without the use of oxygen. It only produces a small amount of ATP compared to aerobic respiration. Examples of fermentation include alcoholic fermentation, in which yeast converts glucose to ethanol and carbon dioxide, and lactic acid fermentation, which occurs in our muscles during intense exercise.

Answer 2

 this can only happen if there is oxygen around, oxygen is toxic to organisms that are obligate anaerobes and is not required by facultative anaerobic organisms. in the absence of oxygen, one of the fermentation pathways occurs in order to regenerate NAD+; lactic acid fermentation is one of these pathways.