Name two serious diseases caused by viruses.

Explanation

**Step-by-Step Text Solution:**

1. **Understanding Viruses**: Viruses are microorganisms that are not visible to the naked eye and require a microscope to be seen. They are smaller than bacteria and can cause various diseases.

2. **Identifying Serious Diseases**: When asked to name serious diseases caused by viruses, we should consider those that have significant health impacts.

3. **First Disease - Polio**: One serious disease caused by a virus is Polio. It is caused by the poliovirus and can lead to severe complications, including paralysis.

...