Which one of the following statements is wrong ?

Options

A. Algae increase the level of dissolved oxygen in the immediate environment
B. Algin is obtained from red algae , and carrageenan from brown algae
C. Agar - agar is obtained from Gelidium and Gracilaria
D. Leminaria and Sargassum are used as food

Answer

To solve the question "Which one of the following statements is wrong?", we will analyze each statement provided in the options one by one.

### Step-by-Step Solution:

1. **Statement 1: Alga increases the level of dissolved oxygen in the immediate environment.**
- **Analysis:** Algae are photosynthetic organisms. During photosynthesis, they absorb carbon dioxide and release oxygen. Therefore, this statement is true.
- **Conclusion:** This statement is not wrong.

2. **Statement 2: Algin is obtained from red alga and carrageenan is obtained from green alga.**
- **Analysis:** Algin is actually obtained from brown algae (Phaeophyceae), not red algae. Carrageenan, on the other hand, is derived from red algae (Rhodophyta). Thus, this statement is incorrect.
- **Conclusion:** This statement is wrong.

3. **Statement 3: Agar agar is obtained from Gelidium and Gracilaria.**
- **Analysis:** Agar agar is indeed obtained from red algae, specifically from the genera Gelidium and Gracilaria. This statement is true.
- **Conclusion:** This statement is not wrong.

4. **Statement 4: Laminaria and Sargassum are used as food.**
- **Analysis:** Both Laminaria and Sargassum are brown algae and are cultivated as food. This statement is true.
- **Conclusion:** This statement is not wrong.

### Final Conclusion:
The only wrong statement among the options is **Statement 2**: "Algin is obtained from red alga and carrageenan is obtained from green alga."