The final electron acceptor at the end of the electron transport chain is .

The final electron acceptor at the end of the electron transport chain is oxygen (O2).

Here's the step-by-step process:

1. The electron transport chain is the last component of aerobic respiration and is the only part of glucose metabolism that uses atmospheric oxygen.

2. It is a series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions. This process simultaneously drives the transfer of protons (H+ ions) across a membrane.

3. These transferred electrons reduce the oxygen molecules to water (H2O).

4. In the process, the protons form a gradient, which is used by enzymes called ATP synthases to generate ATP. This is known as oxidative phosphorylation.

5. Therefore, oxygen is the final electron acceptor at the end of the electron transport chain. It accepts the electrons that have been passed along the chain, and in doing so, gets reduced to form water.