An organism without true nucleus is

Options

A. Bacterium
B. Archaebacterium
C. Cyanobacterium
D. All the above.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for an organism that does not have a true nucleus. This indicates we are looking for a type of organism that lacks a membrane-bound nucleus.

2. **Identifying Organism Types**: Organisms can be broadly classified into two categories based on the presence or absence of a true nucleus: prokaryotes and eukaryotes. Prokaryotes do not have a true nucleus, while eukaryotes do.

3. **Defining Prokaryotes**: Prokaryotes are primitive organisms characterized by the absence of a membrane-bound nucleus. The genetic material in prokaryotes is not enclosed within a nuclear membrane. Instead, it is located in a region of the cell called the nucleoid.

4. **Kingdom Monera**: The only kingdom that consists of prokaryotic organisms is Kingdom Monera. This kingdom includes all bacteria, which can be further classified into different types, such as:
- Eubacteria (common bacteria)
- Archaebacteria (extremophiles like methanogens and thermoacidophiles)
- Cyanobacteria (also known as blue-green algae, which perform photosynthesis but are not true algae).

5. **Conclusion**: Therefore, the organism without a true nucleus is a member of Kingdom Monera, which encompasses all prokaryotic organisms, including various types of bacteria.

6. **Final Answer**: The correct answer to the question is that an organism without a true nucleus is a prokaryote, specifically a member of Kingdom Monera.

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