Pyruvic acid is the initial substrate of

Options

A. Glycolysis
B. Electron transport chain
C. Kreb's cycle
D. Link reaction

Answer

To solve the question "Pyruvic acid is the initial substrate of", we can follow these steps:

### Step 1: Understand the Role of Pyruvic Acid
Pyruvic acid is a key intermediate in several metabolic pathways. It is produced during glycolysis, which is the breakdown of glucose.

**Hint:** Remember that pyruvic acid is formed from glucose during glycolysis.

### Step 2: Analyze the Options
We need to evaluate each option provided in the question to determine which pathway uses pyruvic acid as its initial substrate.

1. **Glycolysis**: This is incorrect because pyruvic acid is the product of glycolysis, not the substrate.

**Hint:** Glycolysis converts glucose into pyruvic acid.

2. **Electron Transport Chain**: This is also incorrect. The electron transport chain does not use pyruvic acid directly; it uses electron carriers produced from earlier metabolic processes.

**Hint:** The electron transport chain is involved in ATP production but does not start with pyruvic acid.

3. **Krebs Cycle (Citric Acid Cycle)**: This is incorrect as well. The initial substrate of the Krebs cycle is Acetyl-CoA, which is derived from pyruvic acid but is not pyruvic acid itself.

**Hint:** Acetyl-CoA is formed from pyruvic acid before entering the Krebs cycle.

4. **Link Reaction**: This is the correct answer. The link reaction (or pyruvate decarboxylation) converts pyruvic acid into Acetyl-CoA, making pyruvic acid the initial substrate for this reaction.

**Hint:** The link reaction connects glycolysis to the Krebs cycle by converting pyruvic acid into Acetyl-CoA.

### Conclusion
The correct answer is that pyruvic acid is the initial substrate of the Link Reaction.

**Final Answer:** The initial substrate of the Link Reaction is pyruvic acid.