Bacteria continue to live under conditions which resemble the conditions that prevailed on primitive earth, are

Options

A. PPLO
B. Archaebacteria
C. Cyanobacteria
D. Chlamydia

Answer

To answer the question regarding which bacteria can survive under conditions resembling those of primitive Earth, we can follow these steps:

### Step 1: Understand the Characteristics of Primitive Earth
Primitive Earth was characterized by extreme conditions, including high temperatures, high salinity, and volcanic activity. Any organism that can thrive in such environments may be considered similar to those that existed during that time.

### Step 2: Analyze the Options Given
1. **PPLO (Pleuropneumonia-like Organism)**: This is a type of Mycoplasma that is pathogenic and causes pneumonia in humans. It does not thrive in extreme conditions and is not representative of primitive Earth.

2. **Archaebacteria**: These are ancient bacteria that can survive in extreme environments, such as high temperatures (thermophiles), high salinity (halophiles), and acidic conditions. They are considered the closest living relatives to the earliest forms of life on Earth.

3. **Cyanobacteria**: Also known as blue-green algae, these organisms are photosynthetic and typically found in moist soils and aquatic environments. They do not specifically thrive in the extreme conditions of primitive Earth.

4. **Chlamydia**: This is a pathogenic bacterium that causes infections in humans. It does not survive in extreme environments and is not representative of conditions on primitive Earth.

### Step 3: Identify the Correct Answer
Given the characteristics of each option, **Archaebacteria** is the correct answer. They are known for their ability to survive in harsh conditions that resemble those of primitive Earth.

### Conclusion
The bacteria that continue to live under conditions resembling those that prevailed on primitive Earth are **Archaebacteria**.

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