Final answer:
The compound that accepts electrons from FADH2 in the electron transport chain is ubiquinone (Q), also known as coenzyme-Q, occurring at Complex II. Ubiquinone carries the electrons to Complex III, resulting in fewer ATP molecules compared to NADH since Complex I's proton pump is bypassed.
Step-by-step explanation:
The student asked about the compound that accepts electrons from FADH2 in the electron transport chain. In this process, FADH2 oxidizes to FAD, and its electrons are transferred to ubiquinone (Q), which is also known as coenzyme-Q. This step occurs at Complex II, which contains the enzyme succinate dehydrogenase from the citric acid cycle. Ubiquinone then becomes ubiquinol (QH₂) as it accepts electrons and can move freely in the hydrophobic core of the inner mitochondrial membrane. Next, ubiquinol transfers its electrons to Complex III in the electron transport chain.
Since FADH2 bypasses Complex I, the number of ATP molecules produced from its electrons is fewer compared to those produced from NADH. This is because the proton pump in Complex I is not utilized, which results in pumping fewer protons across the inner mitochondrial membrane.