How do aerobic respiration and fermentation compare with respect to the efficiency of energy production?
Aerobic respiration produces 34-36 ATP, depending on efficiency. Fermentation doesn't produce any new ATP. However glycolysis, which precedes both aerobic respiration and fermentation, produces a net gain of 2ATP.
Lactic Acid Fermentation
Aerobic Respiration vs. Lactic Acid Fermentation:
Note that the 2ATP of fermentation are from glycolysis.