What are the four steps of anaerobic respiration?

The correct answer includes steps fundamental to the process of anaerobic respiration. Analyzing this process reveals that anaerobic respiration primarily involves glycolysis followed by fermentation.

Glycolysis is the first step, where glucose is broken down into pyruvate, generating a small amount of ATP and NADH in the absence of oxygen. In the case of anaerobic conditions, oxygen is not used for further breakdown of pyruvate through pathways like the Krebs cycle or the electron transport chain, which are part of aerobic respiration. Instead, pyruvate undergoes fermentation, a process that regenerates NAD+ and allows glycolysis to continue by converting pyruvate into other compounds, like lactic acid or ethanol, depending on the organism.

Though the Krebs cycle and the electron transport chain typically play roles in aerobic respiration, they are not involved in anaerobic respiration, which is why the other options presented do not accurately depict the anaerobic process. Thus, the correct option aligns with the key stages of anaerobic respiration: glycolysis followed by fermentation.