Questions: Which of the following organisms have only one photosystem? Chloroplasts Most plants Most algae Anoxygenic bacteria

The answer is the fourth one (D): anoxygenic bacteria.

Explanation for each option:

1. Chloroplasts: Incorrect. Chloroplasts, found in plants and algae, contain two photosystems, Photosystem I and Photosystem II, which are essential for oxygenic photosynthesis.

2. Most plants: Incorrect. Most plants perform oxygenic photosynthesis, which involves two photosystems (Photosystem I and Photosystem II) to convert light energy into chemical energy.

3. Most algae: Incorrect. Like plants, most algae also perform oxygenic photosynthesis using two photosystems.

4. Anoxygenic bacteria: Correct. Anoxygenic bacteria, such as purple and green sulfur bacteria, have only one photosystem. They perform photosynthesis without producing oxygen, using a single photosystem to capture light energy.

In summary, anoxygenic bacteria are the organisms that have only one photosystem.