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

Options

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

Answer

To solve the question regarding the kingdom that includes blue-green algae, nitrogen-fixing bacteria, and methanogenic archaebacteria in the five-kingdom classification system, follow these steps:

### Step-by-Step Solution:

1. **Understand the Five-Kingdom Classification**: The five-kingdom classification system includes Monera, Protista, Fungi, Plantae, and Animalia. Each kingdom has distinct characteristics.

2. **Identify the Organisms in the Question**: The question mentions:
- Blue-green algae (also known as cyanobacteria)
- Nitrogen-fixing bacteria
- Methanogenic archaebacteria

3. **Analyze the Characteristics of Each Kingdom**:
- **Monera**: This kingdom includes all prokaryotic organisms, which are unicellular and lack a defined nucleus. It encompasses bacteria (including nitrogen-fixing bacteria) and archaea (including methanogenic archaebacteria).
- **Protista**: This kingdom consists of eukaryotic organisms, which can be unicellular or multicellular, such as amoebas and algae, but does not include the organisms in the question.
- **Fungi**: This kingdom includes organisms like mushrooms and yeast, which are also eukaryotic and do not include the organisms mentioned in the question.
- **Plantae**: This kingdom includes all plants, which are multicellular eukaryotes that perform photosynthesis, and does not include the organisms in the question.

4. **Determine the Correct Kingdom**: Since blue-green algae, nitrogen-fixing bacteria, and methanogenic archaebacteria are all prokaryotic and fit within the characteristics of the Monera kingdom, the correct answer is Monera.

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