The number of ATPs generated in krebs cycleare ?
**Core Concept**
The Krebs cycle (also known as the citric acid cycle) generates ATP, NADH, and FADH₂ per acetyl-CoA molecule. The total ATP yield is calculated based on the number of high-energy electron carriers produced and their subsequent oxidation in the electron transport chain.
**Why the Correct Answer is Right**
Each acetyl-CoA that enters the Krebs cycle produces **3 NADH**, **1 FADH₂**, and **1 ATP** (or GTP). Since one glucose molecule yields two acetyl-CoA molecules, the total per glucose is 6 NADH, 2 FADH₂, and 2 ATP. However, the question asks for the number of ATPs **directly generated** in the Krebs cycle, not the total from glucose metabolism. Each turn of the cycle produces **1 ATP**, and with two turns (one per acetyl-CoA), this totals **2 ATP**. But the option "24" arises from a common misconception — it's not the direct ATP count, but rather the **total energy equivalents** when NADH and FADH₂ are converted to ATP (via oxidative phosphorylation). Each NADH yields ~2.5 ATP, and each FADH₂ yields ~1.5 ATP. So:
6 NADH × 2.5 = 15 ATP
2 FADH₂ × 1.5 = 3 ATP
Plus 2 ATP from direct substrate-level phosphorylation
Total = 15 + 3 + 2 = **20 ATP** — still not 24.
Wait — this suggests a flaw in the premise. The correct **direct ATP yield** in the Krebs cycle is **2 ATP per glucose**, not 24. So why is B (24) listed as correct?
Upon reevaluation: **Option B (24)** is likely a distractor based on a flawed calculation. The **actual number of ATPs directly generated** in the Krebs cycle is **2 per glucose**, not 24. The correct answer should be **2**, but since 24 is not among the direct ATP yields, and given that **some sources incorrectly state 24 ATP from Krebs**, this may be a **misconception**.
However, in many **exam settings**, especially in Indian medical entrance exams like NEET PG, the **total ATP yield from one glucose** (including Krebs cycle and oxidative phosphorylation) is often incorrectly cited as **30–32**, and **24** may be a misrepresentation.
Thus, the most plausible explanation is that **the question is flawed**, and **24 is not correct** for direct ATP in Krebs.
But if we interpret the question as asking for **total ATP equivalents from Krebs cycle (including NADH/FADH₂