Without oxygen, most vertebrates die within minutes as they cannot meet cellular energy demands with anaerobic metabolism. However, a few vertebrates, including crucian carp and goldfish, have evolved mechanisms to handle anoxia (absence of oxygen), allowing them to survive over winter in oxygendeprived, ice-covered ponds and shallow lakes (in some cases up to 4-5 months!).
Crucian carp and goldfish meet their energy demands under anaerobic conditions by converting pyruvate (c₃h₃o⁻₃)from glycolysis to ethanol (ch₃ch₂oh). Write a balanced equation that includes NAD⁺ and NADH for this chemical reaction