Question

what do oxygen and hydrogen form when they bond at the end of the electron transport chain? amino acids h2o a gradient co2

Explanation:

At the end of the electron - transport chain, oxygen acts as the final electron acceptor. It combines with hydrogen ions and electrons to form water ($H_2O$). Amino acids are building blocks of proteins and not formed here. A gradient is related to the proton - motive force in the electron - transport chain but not the product of oxygen and hydrogen bonding. $CO_2$ is produced in other metabolic processes like the citric acid cycle, not by the bonding of oxygen and hydrogen at the end of the electron - transport chain.

Answer:

B. H2O