In five-kingdom classification system, the kingdom that includes, the blue-green algae, nitrogen-fixing bacteria and methanogenic archaebacteria is

Options

A. Plantae
B. Fungi
C. Protista
D. Monera

Answer

**Step-by-Step Solution:**

1. **Understanding the Five-Kingdom Classification System**: The five-kingdom classification system was proposed by Robert Whittaker and includes the kingdoms Monera, Protista, Fungi, Plantae, and Animalia.

2. **Identifying the Organisms in the Question**: The question mentions three specific types of organisms:
- Blue-green algae (also known as cyanobacteria)
- Nitrogen-fixing bacteria
- Methanogenic archaebacteria

3. **Analyzing the Characteristics of Each Organism**:
- **Blue-green algae (Cyanobacteria)**: These are photosynthetic autotrophs that contain chlorophyll and can perform photosynthesis.
- **Nitrogen-fixing bacteria**: These bacteria are capable of converting atmospheric nitrogen into a form that plants can use, and they are often found in the root nodules of legumes.
- **Methanogenic archaebacteria**: These are a type of archaea that produce methane as a metabolic byproduct in anoxic conditions.

4. **Determining the Kingdom**: In the five-kingdom classification:
- **Monera** is the kingdom that includes all prokaryotic organisms. This kingdom encompasses:
- Archaebacteria (including methanogens)
- Eubacteria (which includes nitrogen-fixing bacteria)
- Cyanobacteria (blue-green algae)

5. **Conclusion**: Based on the characteristics and classification of the mentioned organisms, they all belong to the kingdom **Monera**.

**Final Answer**: The kingdom that includes blue-green algae, nitrogen-fixing bacteria, and methanogenic archaebacteria is **Monera**.

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