Alginic acid is present in the cell wall of

Options

A. bacillariophyceae
B. Euglena
C. Laminaria
D. Diatoms

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about the presence of alginic acid in the cell wall of which organism.

2. **Identifying the Organisms**: The options provided (though not listed in the question) likely include various types of algae and possibly other organisms.

3. **Classifying Algae**: Algae are classified based on their pigmentation into three main groups:
- **Chlorophyceae (Green Algae)**: Known for having cellulose and pectin in their cell walls.
- **Pheophyceae (Brown Algae)**: Known for having cellulose and alginic acid in their cell walls.
- **Rhodophyceae (Red Algae)**: Known for having cellulose, pectin, and polysulfate esters in their cell walls.

4. **Focusing on Alginic Acid**: Since the question specifically mentions alginic acid, we need to focus on the group of algae that contains this compound.

5. **Identifying the Correct Group**: Alginic acid is found in the cell walls of brown algae (Pheophyceae).

6. **Identifying the Specific Organism**: Among the brown algae, Laminaria is a well-known example that contains alginic acid in its cell wall.

7. **Conclusion**: Therefore, the correct answer to the question is that alginic acid is present in the cell wall of **Laminaria**.

### Final Answer:
Alginic acid is present in the cell wall of **Laminaria**.

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