Many blue green algae occur in thermal spring (hot water spring). The temperature tolerance of these algae have been attributed to their

Options

A. Cell wall structure
B. Modern cell organisation
C. Mitochondrial structure
D. Branched chain lipids in the cell membranes

Answer

**Step-by-Step Solution:**

1. **Understanding the Environment**: Recognize that thermal springs are hot water springs characterized by high temperatures. This environment is extreme and can be inhospitable to many organisms.

2. **Identifying the Organisms**: Note that blue-green algae, also known as cyanobacteria, are capable of thriving in such extreme conditions. These organisms are classified as extremophiles, which are adapted to survive in extreme environments.

3. **Analyzing Temperature Tolerance**: The question asks about the specific adaptation that allows blue-green algae to tolerate high temperatures found in thermal springs.

4. **Evaluating the Options**: The options provided are:
- Cell wall structure
- Modern cell organization
- Mitochondrial structure
- Branched chain lipids in the cell membrane

5. **Determining the Correct Adaptation**: Among the options, branched chain lipids in the cell membrane are known to enhance the stability of the cell membrane under extreme temperature conditions. These lipids help maintain membrane integrity and function at high temperatures.

6. **Conclusion**: Therefore, the temperature tolerance of blue-green algae in thermal springs is attributed to the presence of branched chain lipids in their cell membrane.

**Final Answer**: Branched chain lipids in the cell membrane.

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