Question

The energy releasing metabolic process in which subrate is oxidised without an external electron acceptor...?
1.glycolysis 2.fermentation 3.aerobic respiration 4.photorespiration

Answer 1

The correct answer is 2) Fermentation

Fermentation process consumes NADH2 and e- acceptor is not used, rather released as NAD+. While glycolysis uses external e- acceptor as NAD+. Although fermentation also starts with glycolysis but at the end of fermentation process NAD+ is regenerated for next round of glycolysis.​

Glycolysis is itself a part of aerobic respiration and so external electron acceptor is also used in aerobic respiration. Photorespiation occurs in plants, which is not like normal respiratory process in which energy is released.