Bacteria are considered primitive organisms because they

Options

A. Possess incipent nucleus
B. Are small, microscopic plants, which are not seen by the naked eyes
C. Cause serious diseases to human being, domesticated animals and crop plants
D. Produce endospores which are very resistant to adverse conditions

Answer

**Step-by-Step Solution:**

1. **Understanding Bacteria as Primitive Organisms**: Bacteria are considered primitive organisms because they are among the earliest forms of life that evolved on Earth. They appeared during a time when the atmosphere was very different from what it is today.

2. **Evolution of Nutritional Types**: The first bacteria were heterotrophs, which means they obtained their energy by consuming organic molecules. This was the initial form of nutrition that evolved.

3. **Energy Acquisition**: Prokaryotes, which include bacteria, obtained their energy through fermentation of organic molecules. This process was crucial in the primitive world where the atmosphere was reducing.

4. **Transition to Autotrophs**: Over time, there was a decrease in heterotrophic organisms and an increase in autotrophic organisms. Autotrophs can produce their own energy, often through photosynthesis or chemosynthesis.

5. **Types of Bacteria**: Two main types of bacteria emerged:
- **Chemosynthetic Bacteria**: These bacteria derive energy from inorganic molecules rather than organic ones.
- **Photosynthetic Bacteria**: These bacteria use sunlight to produce energy.

6. **Characteristics of Bacteria**: Bacteria are characterized by having an "incipient nucleus," which refers to a nucleoid. This is an immature nucleus that lacks a nuclear membrane, distinguishing them from more complex eukaryotic cells.

7. **Conclusion**: The reason bacteria are considered primitive organisms is primarily due to their simple cellular structure, specifically the presence of an incipient nucleus, which lacks a defined nuclear membrane.

**Final Answer**: Bacteria are considered primitive organisms because they possess an incipient nucleus (nucleoid), which is a characteristic of prokaryotic cells.

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