Highly polluted waters have

Options

A. high Algal Genus index
B. low Algal Genus index
C. no algae at all
D. a few algal genera and a few bacteria

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks about the characteristics of highly polluted waters, specifically in relation to algal presence and oxygen levels.

2. **Analyzing Algal Presence**: Algae are photosynthetic organisms that produce oxygen as a byproduct of photosynthesis. In healthy aquatic environments, a balanced presence of algae indicates good water quality.

3. **Pollution and Oxygen Levels**: In highly polluted waters, the concentration of oxygen is typically low. This is because pollution can lead to the death of aquatic plants and algae, which in turn reduces oxygen production.

4. **Algal Index Implications**:
- A **high algal genus index** indicates a diverse and abundant presence of algae, which correlates with higher oxygen levels and suggests a less polluted environment.
- A **low algal genus index** suggests fewer algae, which correlates with lower oxygen levels and indicates a more polluted environment.

5. **Evaluating Options**:
- **High algal genus index**: This option is incorrect for highly polluted waters.
- **Low algal genus index**: This option is correct as it indicates low oxygen levels and suggests pollution.
- **No algae at all**: This option is incorrect because some algae will still be present in polluted waters.
- **A few algal genera and a few bacteria**: This option is also incorrect as it does not accurately represent the state of highly polluted waters.

6. **Conclusion**: The correct answer is **low algal genus index**, which indicates that highly polluted waters have fewer algae and lower oxygen levels.

**Final Answer**: Highly polluted waters have a low algal genus index.

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