Complex II, also known as succinate dehydrogenase, is an essential enzyme in the electron transport chain of cellular respiration. It plays a crucial role in converting succinate to fumarate while simultaneously transferring electrons to ubiquinone (coenzyme Q), which helps generate energy in the form of ATP. Unlike other complexes in the electron transport chain, Complex II is unique because it is also part of the Krebs cycle (or citric acid cycle). This dual role allows it to link the processes of energy production and metabolism, making it vital for efficient cellular function and energy balance.