The first process in breaking down glucose is :

Options

A. the Krebs cycle
B. glycolysis
C. electron transport system
D. fermentation

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the first process involved in breaking down glucose during cellular respiration.

2. **Identifying the Process**: The initial step in the breakdown of glucose is known as glycolysis.

3. **Defining Glycolysis**: Glycolysis is a metabolic pathway that converts glucose into two molecules of pyruvate. It is the first step in the process of cellular respiration.

4. **Characteristics of Glycolysis**:
- **Anaerobic Process**: Glycolysis does not require oxygen, which means it can occur in both aerobic and anaerobic conditions.
- **Enzymatic Reactions**: Glycolysis consists of a series of enzymatic reactions that facilitate the breakdown of glucose.

5. **Outcome of Glycolysis**: The end products of glycolysis are two molecules of pyruvate, along with a small yield of ATP (energy currency of the cell) and NADH (an electron carrier).

6. **Conclusion**: Therefore, the first process in breaking down glucose is glycolysis.

**Final Answer**: The first process in breaking down glucose is glycolysis.

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