Which of the following contains copper ?

Options

A. Quinone
B. Plastoquinone
C. Plastocyanin
D. Cyt `b_(5)`.

Answer

To determine which of the following options contains copper, we will analyze each option provided:

1. **Quinone**: Quinones are organic compounds that do not contain copper. They are aromatic compounds and are not associated with copper in their structure. Therefore, this option is incorrect.

2. **Plastoquinone**: Plastoquinone is a type of quinone that is derived from isoprenoid compounds. Similar to quinone, plastoquinone does not contain copper. It is also incorrect.

3. **Plastocyanine**: Plastocyanine is a well-known electron carrier in photosynthesis that contains copper. It plays a crucial role in transferring electrons from the cytochrome b6f complex to photosystem I (P700). Therefore, this option is correct.

4. **Cytochrome b5**: Cytochrome b5 is an electron carrier that contains heme, which is an iron-containing compound. It does not contain copper. Thus, this option is also incorrect.

Based on this analysis, the correct answer is **Plastocyanine** (Option C), as it is the only one among the options that contains copper.

### Summary of Steps:
1. Analyze each option for the presence of copper.
2. Identify that quinone and plastoquinone do not contain copper.
3. Confirm that plastocyanine is a copper-containing electron carrier.
4. Note that cytochrome b5 contains iron, not copper.
5. Conclude that plastocyanine is the correct answer.