Question

How do humans generate energy when oxygen is not available?

a. Using Kreb’s Cycle only
b. Using the Electron Transport Chain only
c. Using alcoholic fermentation
d. Using lactic acid fermentation

Answer 1

When Oxygen is not available, the cell is forced to produce energy (=ATP) through ANAEROBIC processes, that produce much less energy (about 15 times less), than AEROBIC processes. ... The electron transport chain (ETC) allows the cell to produce energy (ATP) by creating a proton gradient across the mitochondrial membrane. So B.