Which of the following processes produce the maximum amount of ATP on the aerobic breakdown of one molecule of glucose ?

Options

A. Glycolysis
B. Kreb's
C. Electron transport system
D. Fermentation

Answer

To determine which process produces the maximum amount of ATP during the aerobic breakdown of one molecule of glucose, we need to analyze the different stages involved in aerobic respiration. The main processes include glycolysis, the Krebs cycle (also known as the citric acid cycle), and the electron transport chain.

### Step-by-Step Solution:

1. **Understanding Aerobic Respiration**:
- Aerobic respiration involves the complete breakdown of glucose in the presence of oxygen, resulting in the production of ATP, carbon dioxide, and water.

2. **Identifying the Processes**:
- The main processes involved in aerobic respiration are:
- Glycolysis
- Pyruvate Decarboxylation
- Krebs Cycle (TCA Cycle)
- Electron Transport Chain (ETC)

3. **Calculating ATP Yield from Each Process**:
- **Glycolysis**:
- Converts one molecule of glucose into two molecules of pyruvate.
- Produces a net gain of **2 ATP** and **2 NADH** (which can be converted to ATP in the ETC).
- **Pyruvate Decarboxylation**:
- Each pyruvate is converted to acetyl CoA, producing **2 NADH** (1 from each pyruvate).
- This results in an additional **5 ATP** (since each NADH can yield approximately 2.5 ATP in the ETC).
- **Krebs Cycle**:
- Each acetyl CoA enters the Krebs cycle, producing **3 NADH**, **1 FADH2**, and **1 ATP** per cycle.
- For two acetyl CoA (from one glucose), this results in **6 NADH**, **2 FADH2**, and **2 ATP**.
- This translates to **15 ATP** from NADH and **4 ATP** from FADH2, plus **2 ATP** directly from the cycle, totaling **21 ATP**.
- **Electron Transport Chain**:
- The NADH and FADH2 produced in the previous steps are used in the ETC to produce ATP.
- Total ATP from all processes combined is approximately **38 ATP**.

4. **Conclusion**:
- Among the processes listed, the **Electron Transport Chain** produces the maximum amount of ATP during the aerobic breakdown of glucose, yielding about **34 ATP** from the reduced coenzymes (NADH and FADH2) generated in the earlier steps, in addition to the ATP produced directly in glycolysis and the Krebs cycle.

### Final Answer:
- The process that produces the maximum amount of ATP on the aerobic breakdown of one molecule of glucose is the **Electron Transport Chain**.