Answer:
Anaerobic respiration is a shorter process than aerobic respiration so a complete cycle of anaerobic respiration is shorter than one of aerobic respiration.
Explanation:
Aerobic respiration involves three stages: glycolysis (the breakdown of glucose into pyruvate), the Krebs cycle (the breakdown of pyruvate into carbon dioxide and hydrogen), and the electron transport chain (hydrogen produced in the Krebs cycle bonding to oxygen to form water).
On the other hand, anaerobic respiration has fewer stages. Anaerobic means 'without oxygen', and so the process takes place without needing any oxygen. In anaerobic respiration, glucose is broken down into pyruvate, just like in aerobic respiration, however due to the lack of oxygen, that pyruvate is broken down into either lactic acid (e.g. in humans), or ethanol (e.g. in yeast). This process is called fermentation, and it doesn't take as long as the Krebs cycle and the electron transport chain, so that's why anaerobic respiration is more rapid than aerobic respiration.
