Fermentation Original Scenario-Based Download PDF

Questions

1. 1.

   A xenobiology research crew studying a sealed, subterranean biosphere discovers an extremophilic bacterium, Cryoanaerobacter, which survives in anoxic cavern pools strictly through alcoholic fermentation. Biochemical assays confirm that the bacterium generates all of its cellular ATP through glycolysis and subsequently converts pyruvate into ethanol and carbon dioxide in two enzymatic steps. When a laboratory inhibitor specifically blocks the second step—the reduction of acetaldehyde to ethanol—the cells rapidly deplete their ATP reserves and halt all sugar metabolism. What primary biochemical failure directly prevents glycolysis from continuing under this inhibition?

   • A) The cells can no longer activate glucose because hexokinase directly requires ethanol as an essential allosteric cofactor.
   • B) The regeneration of NAD+ from NADH is blocked, causing glycolysis to halt due to a lack of available electron acceptors.
   • C) The decarboxylation of pyruvate fails to release free phosphate groups needed for substrate-level phosphorylation.
   • D) The accumulation of acetaldehyde reverses the mitochondrial proton gradient across the inner membrane.