Red coloured pigment bacteriorhodopsin is present in :

Options

A. Methanogens
B. Halophiles
C. Thermoacidophiles
D. Cyanobacteria

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks where the red-colored pigment bacteriorhodopsin is found.

2. **Identifying the Options**: The options provided include methanogens, halophiles, thermoacidophiles, and cyanobacteria. All these organisms are part of the Monera kingdom, which consists of prokaryotes.

3. **Defining Bacteriorhodopsin**: Bacteriorhodopsin is an integral membrane protein that acts as a light-driven proton pump. It is known for its role in energy production in certain microorganisms.

4. **Locating Bacteriorhodopsin**: Bacteriorhodopsin is primarily found in the purple membrane of halophilic archaea. This membrane can occupy a significant portion of the cell surface area and is involved in the photosynthetic process.

5. **Eliminating Incorrect Options**:
- Methanogens are known for producing methane and do not contain bacteriorhodopsin.
- Thermoacidophiles thrive in hot and acidic environments but are not specifically associated with bacteriorhodopsin.
- Cyanobacteria, while photosynthetic, belong to Eubacteria and do not produce bacteriorhodopsin.

6. **Identifying the Correct Answer**: Since bacteriorhodopsin is associated with halophiles (salt-loving archaea), the correct answer is halophiles.

**Final Answer**: Bacteriorhodopsin is present in halophiles.

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