What type of metabolism occurs in the absence of oxygen, leading to the production of lactic acid?

Anaerobic metabolism is the type of metabolism that occurs in the absence of oxygen. This process allows cells to generate energy without the need for oxygen, primarily by breaking down glucose. In anaerobic metabolism, glucose is converted into energy through glycolysis, which results in the production of pyruvate. When oxygen levels are low, such as during intense physical activity, pyruvate is then further converted into lactic acid.

Lactic acid buildup is commonly associated with muscle fatigue and discomfort, which is why it is frequently referenced in athletic contexts. This metabolic pathway is essential as it provides a quick source of energy for cells when oxygen is not readily available, although it is less efficient than aerobic metabolism, which requires oxygen to produce energy.

In contrast, aerobic metabolism requires oxygen and produces carbon dioxide and water as byproducts. Oxidative metabolism, which is a part of aerobic metabolism, specifically refers to the use of oxygen to produce energy from substrates. Cellular respiration encompasses both anaerobic and aerobic processes, but since the question specifically asks for metabolism in the absence of oxygen, anaerobic metabolism is the most accurate choice.