Answer
The final acceptor during fermentation is a pyruvate derivative such as acetaldehyde and the final acceptor during aerobic respiration is oxygen.
Work Step by Step
To find the final electron acceptors, look at the figures for the electron transport chain (Fig. 9.15) and fermentation (Fig. 9.18) to see the last molecule to receive the electrons ultimately from NADH, when it returns to being $NAD^{+}$.
