Final answer:
Glycolysis is the metabolic pathway common to both cellular respiration and fermentation, generating ATP without requiring oxygen. It allows energy production in aerobic and anaerobic conditions and is a key process in diverse organisms including humans, where aerobic respiration is primary but lactic acid fermentation occurs in muscles when oxygen is low.
The correct option is A.
Step-by-step explanation:
Metabolic Pathways Shared by Cellular Respiration and Fermentation
The metabolic pathway that is common to both cellular respiration and fermentation is glycolysis. During glycolysis, a single six-carbon glucose molecule is broken down into two three-carbon molecules of pyruvate.
This process occurs in the cytoplasm of cells and does not require oxygen, allowing it to occur in both aerobic and anaerobic conditions. It generates a small amount of energy in the form of ATP and does not involve the other stages of cellular respiration - the Krebs cycle and the electron transport chain - which are aerobic processes.
Glycolysis is universal and has evolved as a metabolic process found in nearly all living organisms. It enables cells to produce energy, even in the absence of oxygen, which is why it can occur in fermentation as well as aerobic respiration. Furthermore, glycolysis provides precursor molecules and reduced electron carriers for various cellular functions.
In the human body, the type of metabolic process that primarily occurs is aerobic cellular respiration, which includes glycolysis, the Krebs cycle, and the electron transport chain. However, in the absence of oxygen, our muscle cells can perform lactic acid fermentation to regenerate NAD+ and allow glycolysis to continue.
Is Fermentation Aerobic or Anaerobic?
Fermentation is an anaerobic process, meaning it does not require oxygen. Both types of fermentation - alcoholic and lactic acid - and aerobic respiration begin with glycolysis, which explains why fermentation can still proceed in the absence of oxygen.
The correct option is A.