Which of the following statements is false?

Options

A. Chitin, a complex or heteropolysaccharide occurring in exoskeleton of arthopods consists of NAG
B. Glucosamine and N-acetylglucosamine are modified sugar
C. Cellulose shows blue colour when treated with `l_(2)`
D. Starch shows blue colour when treated with `l_(2)`

Answer

**Step-by-Step Solution:**

1. **Identify the Statements:**
- The question asks to determine which statement is false among several provided statements.

2. **Analyze the First Statement:**
- The first statement discusses chitin, describing it as a heteropolysaccharide found in the exoskeleton of arthropods and the cell wall of fungi.
- It mentions that chitin consists of N-acetylglucosamine (NaG).
- **Evaluation:** Chitin is indeed a homopolysaccharide composed of repeating units of N-acetylglucosamine, which means the statement incorrectly categorizes it as a heteropolysaccharide. This statement is false.

3. **Analyze the Second Statement:**
- The second statement claims that glucosamine and N-acetylglucosamine are modified sugars.
- **Evaluation:** This is true because glucosamine is an amino sugar, and adding an acetyl group to it results in N-acetylglucosamine, confirming it as a modified sugar.

4. **Analyze the Third Statement:**
- The third statement claims that cellulose shows blue color when treated with iodine.
- **Evaluation:** This is false. Cellulose does not show a blue color with iodine because its structure does not allow iodine to bind effectively.

5. **Analyze the Fourth Statement:**
- The fourth statement claims that starch shows blue color when treated with iodine.
- **Evaluation:** This is true. Starch, particularly its amylose component, forms a blue complex with iodine.

6. **Conclusion:**
- The false statements identified are the first and third statements. However, the question specifically asks for one false statement, which is the third statement about cellulose.

**Final Answer:**
The false statement is: "Cellulose shows blue color when treated with iodine."

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