Oxygen required for terminal oxidation enters mitochondria as

Options

A. Glucose
B. Activated acetic group
C. Oxygen gas
D. Pyruvic acid

Answer

To answer the question "Oxygen required for terminal oxidation enters mitochondria as," we need to analyze the options provided and understand the process of terminal oxidation.

### Step-by-Step Solution:

1. **Understanding Terminal Oxidation**: Terminal oxidation is the final step in cellular respiration, where oxygen is used to oxidize substrates and produce water and energy (ATP). This process occurs in the mitochondria.

2. **Identifying the Role of Oxygen**: Oxygen is essential for this process as it acts as the final electron acceptor in the electron transport chain, which is located in the inner mitochondrial membrane.

3. **Evaluating the Options**:
- **Glucose**: This is a substrate that is broken down during glycolysis and does not enter the mitochondria as oxygen.
- **Activated Acetic Group**: This refers to acetyl-CoA, which is involved in the Krebs cycle but is not the form in which oxygen enters.
- **Oxygen Gas**: This is the molecular form of oxygen (O2) that enters the mitochondria directly from the bloodstream.
- **Pyruvic Acid**: This is the end product of glycolysis and is converted to acetyl-CoA before entering the Krebs cycle, not the form in which oxygen enters.

4. **Conclusion**: The only correct option is **oxygen gas**, as it is the form in which oxygen enters the mitochondria for the purpose of terminal oxidation.

### Final Answer:
Oxygen required for terminal oxidation enters mitochondria as **oxygen gas**.

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