Which of the following reproduces only inside a host cell?

Options

A. Bacteria
B. Virus
C. Amoeba
D. Fungus

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which microorganism reproduces only inside a host cell. This means we need to identify the organism that cannot reproduce outside of a living cell.

2. **Analyzing the Options**:
- **Bacteria**: Bacteria can reproduce both inside and outside a host. They can perform asexual reproduction independently of a host cell.
- **Virus**: Viruses are unique in that they cannot reproduce on their own. They require a host cell to replicate. Outside of a host, they exist in a dormant state and cannot multiply.
- **Amoeba**: Amoebas are free-living microorganisms that can reproduce independently in their environment, such as in water bodies.
- **Fungi**: Fungi can live both inside and outside of a host. They can reproduce independently and do not rely solely on a host for reproduction.

3. **Identifying the Correct Answer**: Among the options, the virus is the only microorganism that reproduces exclusively inside a host cell. It utilizes the host's cellular machinery to replicate its genetic material and produce new virus particles.

4. **Conclusion**: Therefore, the correct answer is the virus.

**Final Answer**: The microorganism that reproduces only inside a host cell is the **virus**.

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