__________present in the cell wall of brown algae prevents dying or freezing.

Explanation

**Step-by-Step Solution:**

1. **Identify the Organism**: The question refers to brown algae, which are classified under the group known as Pheophyceae.

2. **Understand the Structure**: Brown algae are aquatic photosynthetic organisms that have a cell wall, similar to plants.

3. **Components of the Cell Wall**: The cell wall of brown algae is primarily composed of cellulose, which is a common structural component in the cell walls of many plants.

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