What are viruses? Draw a labelled diagram of a virus.

Explanation

### Step-by-Step Solution

**Step 1: Definition of Viruses**
Viruses are microscopic organisms that are considered infectious agents. They are much smaller than bacteria and cannot be seen with the naked eye. They are unique because they cannot reproduce on their own; they require a host cell to multiply.

**Step 2: Characteristics of Viruses**
- **Microscopic Size**: Viruses are extremely small and can only be viewed under a microscope.
- **Shape Variability**: They can have various shapes, including rod-shaped, spherical, polygonal, and cubical.
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