Out of 38 ATP molecules per glucose, 30 ATP molecules are formed from `NADH//FADH_(2)` in

Options

A. respiratory chain
B. Krebs' cycle
C. oxidative decarboxylation
D. EMP

Explanation

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the formation of 30 ATP molecules from NADH and FADH2 during the breakdown of glucose. We need to identify which cycle is responsible for this production.

2. **Glycolysis**: The first step in glucose metabolism is glycolysis, which occurs in the cytoplasm. One glucose molecule is converted into two pyruvate molecules. During glycolysis, a net gain of 8 ATP molecules is produced.

3. **Krebs Cycle (Citric Acid Cycle)**: The two pyruvate molecules then enter the Krebs cycle, which occurs in the mitochondrial matrix. Each pyruvate molecule produces several high-energy electron carriers, specifically NADH and FADH2.

4. **ATP Production from Pyruvate**: Each pyruvate molecule yields:
- 4 NADH molecules (which can produce 12 ATP, since each NADH yields 3 ATP).
- 1 FADH2 molecule (which can produce 2 ATP).
- 1 GTP (which is equivalent to 1 ATP).

Therefore, for one pyruvate:
- Total ATP from NADH = 4 NADH × 3 ATP/NADH = 12 ATP
- Total ATP from FADH2 = 1 FADH2 × 2 ATP/FADH2 = 2 ATP
- Total ATP from GTP = 1 ATP

Adding these together gives:
- Total ATP per pyruvate = 12 + 2 + 1 = 15 ATP

5. **Total ATP from Two Pyruvate Molecules**: Since glycolysis produces two pyruvate molecules from one glucose molecule, the total ATP produced from both pyruvate molecules in the Krebs cycle is:
- 15 ATP × 2 = 30 ATP

6. **Conclusion**: The 30 ATP molecules formed from NADH and FADH2 are produced during the Krebs cycle. Therefore, the correct answer to the question is the Krebs cycle.

### Answer:
The 30 ATP molecules are formed from NADH and FADH2 in the **Krebs cycle**.

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