Final Answer:
Cells throw away electrons in fermentation because b. The energy required to synthesize organics from electrons is too high.
Step-by-step explanation:
In cellular respiration, cells have two main options for energy production: aerobic respiration, which involves the electron transport chain (ETC) and oxidative phosphorylation, and fermentation. The key difference lies in the fate of electrons generated during glycolysis. In the context of the given question, the most pertinent factor influencing the choice of fermentation over organic synthesis is the high energy cost associated with synthesizing organic compounds from electrons.
During aerobic respiration, electrons are passed through the ETC, leading to the generation of a proton gradient across the inner mitochondrial membrane. The energy released as electrons move through the ETC is harnessed to pump protons across the membrane, creating a proton motive force that ultimately drives the synthesis of ATP. In contrast, fermentation bypasses the ETC and directly converts NADH, produced in glycolysis, back to NAD^+. This process regenerates NAD^+ for use in glycolysis but does not harness the energy from electrons for ATP synthesis.
The energy required for the synthesis of organic compounds from electrons is substantial, and cells may opt for fermentation when immediate energy needs outweigh the benefits of storing energy in the form of ATP. While fermentation provides a rapid means of replenishing NAD^+ and sustaining glycolysis, it foregoes the more efficient energy extraction seen in aerobic respiration. This choice reflects the dynamic balance cells maintain between immediate energy requirements and the long-term benefits of maximizing ATP production through the electron transport chain.