What does the electron transport chain accomplish in cellular respiration?

What does the electron transport chain accomplish in cellular respiration?

• A. Uses the high energy electrons to convert NAD+ to NADH
• B. Uses the high energy electrons from the Krebs cycle to convert ADP into ATP
• C. Synthesize glucose from carbon dioxide and water
• D. Pumps protons across the membrane without any ATP production

Answer: (B)

The main idea is that the electron transport chain transforms the energy carried by high-energy electrons into usable ATP. Those electrons come from NADH and FADH2 produced by earlier steps, especially the Krebs cycle, and their flow through the chain releases energy to pump protons across the inner mitochondrial membrane. This creates a proton gradient that powers ATP synthase to convert ADP and inorganic phosphate into ATP. In other words, the chain’s purpose is to turn the energy stored in electron carriers into ATP, the cell’s energy currency. That’s why this description is the best fit: it ties the electron flow from the Krebs cycle to the production of ATP. The other statements aren’t accurate: glucose isn’t synthesized by the electron transport chain, proton pumping is coupled to ATP generation, and the chain doesn’t start by turning NAD+ into NADH.

The main idea is that the electron transport chain transforms the energy carried by high-energy electrons into usable ATP. Those electrons come from NADH and FADH2 produced by earlier steps, especially the Krebs cycle, and their flow through the chain releases energy to pump protons across the inner mitochondrial membrane. This creates a proton gradient that powers ATP synthase to convert ADP and inorganic phosphate into ATP. In other words, the chain’s purpose is to turn the energy stored in electron carriers into ATP, the cell’s energy currency. That’s why this description is the best fit: it ties the electron flow from the Krebs cycle to the production of ATP. The other statements aren’t accurate: glucose isn’t synthesized by the electron transport chain, proton pumping is coupled to ATP generation, and the chain doesn’t start by turning NAD+ into NADH.