What are the requirements for a single turn of the Krebs Cycle?

The correct choice indicates that one turn of the Krebs Cycle requires 1 Acetyl CoA, 3 NAD+, and 1 FAD+. This is accurate because, during one complete cycle, one molecule of Acetyl CoA enters the cycle, where it is oxidized to produce energy carriers.

Specifically, as Acetyl CoA combines with oxaloacetate to form citrate, the cycle continues through various enzymatic steps that result in the reduction of three NAD+ molecules to NADH, and one FAD molecule to FADH2. Additionally, a molecule of GTP or ATP is also produced during the process, which contributes to the overall energy yield from cellular respiration.

This requirement reflects the primary substrates and products involved in each turn of the Krebs Cycle, emphasizing the cycle's role in energy production through the oxidation of organic molecules. The numbers of NAD+ and FAD+ are specifically critical because they represent the electron carriers that transport high-energy electrons to the electron transport chain, which is essential for ATP synthesis in the mitochondria.