A polysaccharide used as solidyfying agent is

Options

A. pectin
B. silica gel
C. pepton
D. agar

Answer

To solve the question "A polysaccharide used as a solidifying agent is," we will analyze the options given: pectin, silica gel, peptone, and agar.

### Step-by-Step Solution:

1. **Identify the Type of Substance**: The question specifically asks for a polysaccharide. A polysaccharide is a type of carbohydrate that consists of long chains of monosaccharide units.

2. **Analyze the Options**:
- **Pectin**: This is a polysaccharide found in the cell walls of plants, often used as a gelling agent in food.
- **Silica Gel**: This is not a polysaccharide; it is a form of silicon dioxide used as a desiccant.
- **Peptone**: This is a mixture of peptides and amino acids, derived from protein, and is not a polysaccharide.
- **Agar**: This is a polysaccharide obtained from red algae and is widely used as a solidifying agent in microbiological media.

3. **Determine the Correct Answer**: Among the options, agar is the only polysaccharide that is commonly used as a solidifying agent in laboratories for culturing microorganisms.

4. **Conclusion**: Therefore, the correct answer to the question is **agar**.

### Final Answer:
A polysaccharide used as a solidifying agent is **agar**.

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