AP BIOLOGY

Detailed explanation-1: -If oxygen isn’t there to accept electrons (for instance, because a person is not breathing in enough oxygen), the electron transport chain will stop running, and ATP will no longer be produced by chemiosmosis.

Detailed explanation-2: -These low energy molecules cycle back to glycolysis and/or the citric acid cycle, where they pick up more high energy electrons and allow the process to continue. Glycolysis and the citric acid cycle can not occur if there is not NAD+ present to pick up electrons as the reactions proceed.

Detailed explanation-3: -Pyruvate is the electron acceptor in the fermentation process.

Detailed explanation-4: -3. Glycolysis does not require oxygen and can occur under aerobic and anaerobic conditions. However, during aerobic respiration, the two reduced NADH molecules transfer protons and electrons to the electron transport chain to generate additional ATPs by way of oxidative phosphorylation.