Final answer:
The statement that the outer membrane of a mitochondrion is permeable to all small proteins is false, as it has selective porins for molecule passage.
Step-by-step explanation:
The outer membrane of a mitochondrion is indeed permeable to all sorts of small molecules, but it is not as permeable to proteins, including small proteins, as the question suggests. Instead, the mitochondrion's outer membrane contains special proteins known as porins that allow the passage of molecules up to a certain size. Thus, the statement that the outer membrane is permeable to all small proteins is false.
When it comes to electron transport systems, you would find them located in the inner membrane of mitochondria in eukaryotic cells or the cytoplasmic membrane in prokaryotic cells. This is part of the reason why the inner and outer membranes are key to the mitochondrion's function in aerobic respiration, where the inner membrane's structure, including the cristae, provides the necessary surface area for crucial biochemical reactions, including the electron transport chain.