What are oncoviruses?

Explanation

### Step-by-Step Solution:

1. **Definition of Oncoviruses**: Oncoviruses are a specific type of virus that can lead to cancer in humans and animals. The term "onco" is derived from the Greek word "onkos," which means mass or tumor, and "virus" refers to the infectious agents.

2. **Relation to Oncology**: The study of cancer is known as oncology. Oncoviruses are significant in this field as they are directly linked to the development of cancerous growths.

3. **Mechanism of Action**: Oncoviruses can alter normal cellular functions. They do this by activating normal genes (proto-oncogenes) and converting them into oncogenes. Oncogenes are mutated forms of genes that promote uncontrolled cell division and growth, leading to cancer.

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