Fermentation always produces -

Options

A. AMP
B. `NAD^(+)`
C. Pi
D. DNA

Answer

**Step-by-Step Solution:**

1. **Understanding Fermentation**: Fermentation is a metabolic process that occurs in the absence of oxygen (anaerobic conditions). It involves the conversion of sugars, primarily glucose, into energy.

2. **Glycolysis Process**: The first step in fermentation is glycolysis, where glucose is partially oxidized to produce 2 moles of pyruvic acid. During this process, a net gain of 2 moles of ATP and 2 moles of NADH is achieved.

3. **Anaerobic Conditions**: In the absence of oxygen, pyruvic acid undergoes fermentation. The specific type of fermentation can vary; for instance, in alcoholic fermentation, pyruvic acid is converted into ethanol and carbon dioxide.

4. **Conversion of Pyruvic Acid**: During fermentation, pyruvic acid is converted into ethanol. This process also involves the utilization of NADH, which is converted back to NAD+. Specifically, 2 moles of NADH are used, resulting in the formation of 2 moles of NAD+.

5. **Final Products of Fermentation**: The overall products of fermentation include:
- 2 moles of ATP (produced during glycolysis)
- 2 moles of NAD+ (produced from the conversion of NADH)
- Ethanol (the final product of fermentation)
- 1 mole of CO2 (released during the conversion of pyruvic acid to ethanol)

6. **Evaluating the Options**:
- Option 1: AMP - Incorrect, as ATP is produced, not AMP.
- Option 2: NAD+ - Correct, as NADH is converted to NAD+ during fermentation.
- Option 3: PI (inorganic phosphate) - Incorrect, as it is not a product of fermentation.
- Option 4: DNA - Incorrect, as fermentation does not produce DNA.

7. **Conclusion**: The correct answer to the question "Fermentation always produces -" is **NAD+**.

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