Cytochromes are found in

Options

A. entire inner mitochondrial membrane
B. cristae only
C. matrix of mitochondria
D. oxysomes

Answer

### Step-by-Step Solution:

1. **Understanding Cytochromes**:
- Cytochromes are proteins that contain a heme group with a central iron atom. They play a crucial role in cellular respiration, particularly in the electron transport chain (ETC) and redox reactions.

2. **Location of Cytochromes**:
- To determine where cytochromes are found, we need to look at the structure of mitochondria, which is the powerhouse of the cell.

3. **Structure of Mitochondria**:
- Mitochondria have an outer membrane, an inner membrane, and an intermembrane space. The inner membrane is folded into structures called cristae.

4. **Function of Cristae**:
- The cristae are the sites where the electron transport chain occurs. This is where cytochromes are located, facilitating the transfer of electrons and the generation of ATP.

5. **Evaluating Options**:
- **Entire inner mitochondrial membrane**: This option is too broad; cytochromes are specifically located in the cristae.
- **Cristae only**: This is the correct answer, as cytochromes are found in the cristae where the electron transport chain operates.
- **Matrix of mitochondria**: This is incorrect; the matrix contains enzymes for the Krebs cycle but not cytochromes.
- **Auxosomes**: These are structures related to ATP synthesis but are not where cytochromes are found.

6. **Conclusion**:
- Based on the information, the correct answer is that cytochromes are found in the **cristae only**.

### Final Answer:
**Cytochromes are found in the cristae only (Option B).**

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