What is a carcinogen? Name one chemical carcinogen and its target tissue.

Explanation

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

1. **Definition of Carcinogen**: A carcinogen is a substance that is capable of causing cancer in living tissue. These substances can be chemical, physical, or biological agents that lead to the transformation of normal cells into cancerous cells.

2. **Identification of a Chemical Carcinogen**: One well-known chemical carcinogen is tobacco smoke. Tobacco smoke contains various harmful chemicals that can lead to cancer.

3. **Target Tissue of the Carcinogen**: The primary target tissue affected by tobacco smoke is the lungs. The inhalation of tobacco smoke can cause various lung-related diseases, including lung cancer.

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