How many ATP molecules are produced in the Krebs cycle per acetyl-CoA?

• A. 1
• B. 2
• C. 3
• D. 4

Answer: (B)

The question is about how much energy the Krebs cycle directly provides per acetyl-CoA and how that fits into the larger ATP yield.

In one turn of the cycle, energy is captured directly by substrate-level phosphorylation to form one molecule of ATP (listed as GTP in many diagrams). So, the direct ATP produced per acetyl-CoA is one molecule. The cycle also produces three NADH and one FADH2, which don’t become ATP immediately. Those carriers deliver their energy to the electron transport chain, where NADH typically yields about 2.5 ATP and FADH2 about 1.5 ATP, giving roughly 10 ATP equivalents in total per acetyl-CoA when you include the oxidative-phosphorylation stage.

Some exam questions or simplified mark schemes might present a smaller number, but the standard interpretation for ATP directly produced within the Krebs cycle is one per acetyl-CoA, with the remainder of the energy coming later from the electron transport chain.