Conversion of pyruvic acid into lactic acid occurs in

Options

A. Absence of oxygen
B. Presence of NAD
C. Presence of oxidase enzymes
D. None of these

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the conversion of pyruvic acid into lactic acid and the conditions under which this conversion occurs.

2. **Identifying the Process**: The conversion of pyruvic acid into lactic acid is a part of the anaerobic respiration process, specifically fermentation.

3. **Glycolysis**: First, glucose is broken down through a process called glycolysis, which produces pyruvic acid. This occurs regardless of whether oxygen is present or not.

4. **Presence of Oxygen**: If oxygen is present, pyruvic acid is converted into acetyl-CoA, which then enters the Krebs cycle for further energy production.

5. **Absence of Oxygen**: In the absence of oxygen, the pyruvic acid undergoes fermentation. During this process, certain organisms, such as bacteria, convert pyruvic acid into lactic acid.

6. **Conclusion**: Therefore, the conversion of pyruvic acid into lactic acid occurs in the absence of oxygen.

7. **Final Answer**: The correct answer to the question is "in the absence of oxygen."

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