Product of first biological oxidation in Krebs cycle is
Isocitric acid
Oxalosuccinic acid
α -Ketoglutaric acid
Succinic acid

Options

A. Isocitric acid
B. Oxalosuccinic acid
C. `alpha`-Ketoglutaric acid
D. Succinic acid

Answer

To solve the question regarding the product of the first biological oxidation in the Krebs cycle, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Krebs Cycle**: The Krebs cycle, also known as the citric acid cycle (TCA cycle), is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived from carbohydrates, fats, and proteins.

2. **Identify the Starting Point**: The cycle begins with the combination of acetyl-CoA and oxaloacetic acid, which forms citrate (citric acid).

3. **Conversion of Citrate**: Citrate undergoes isomerization to form isocitrate.

4. **First Oxidation Reaction**: The first biological oxidation in the Krebs cycle occurs when isocitrate is oxidized. This reaction converts isocitrate into oxalosuccinic acid.

5. **Further Reactions**: Oxalosuccinic acid is then converted into α-ketoglutaric acid through decarboxylation.

6. **Conclusion**: Therefore, the product of the first biological oxidation in the Krebs cycle is oxalosuccinic acid.

### Final Answer:
The product of the first biological oxidation in the Krebs cycle is **oxalosuccinic acid**.

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