Mitochondria supply most of the necessary biological energy be

Options

A. Breaking of proteins
B. Reduction of `NADP^(+)`
C. Breaking of sugars
D. Oxidising TCA substrates.

Answer

**Step-by-Step Solution:**

1. **Understanding the Role of Mitochondria**: Mitochondria are known as the powerhouses of the cell because they are the primary site of energy production in the form of ATP (adenosine triphosphate).

2. **Identifying Energy Production Pathways**: The main pathways for energy production in mitochondria are the Krebs cycle (also known as the TCA cycle) and oxidative phosphorylation. These processes occur within the mitochondria, specifically in the matrix and the inner membrane.

3. **Examining the Energy Yielding Substrates**: The primary substrates that provide energy include carbohydrates (like glucose), fats, and proteins. Each of these substrates undergoes metabolic processes to enter the mitochondrial pathways.

4. **Metabolism of Carbohydrates**: Carbohydrates, primarily glucose, undergo glycolysis in the cytoplasm to produce pyruvate, which then enters the mitochondria for further processing in the Krebs cycle.

5. **Metabolism of Fats**: Fats are broken down into acetyl CoA, which also enters the Krebs cycle in the mitochondria.

6. **Metabolism of Proteins**: Proteins can be metabolized to form intermediates that enter the Krebs cycle, such as acetyl CoA or other amino acid derivatives.

7. **Evaluating the Options**:
- **Breaking of Proteins**: This option is incorrect because it does not directly explain the energy production process.
- **Reduction of NADP**: This option is also incorrect as it does not directly relate to ATP production.
- **Breaking of Sugar**: This option is misleading as it only refers to carbohydrates and ignores other substrates.
- **Oxidizing TCA Substrate**: This option is correct because it encompasses the overall process of energy production through the Krebs cycle and oxidative phosphorylation, which occurs in the mitochondria.

8. **Conclusion**: The correct answer is that mitochondria supply most of the necessary biological energy by oxidizing TCA substrates.