Define excretion.

Explanation

**Step-by-Step Solution:**

1. **Definition of Excretion**: Excretion is the biological process through which organisms eliminate metabolic waste products from their bodies.

2. **Importance of Excretion**: It is essential for maintaining homeostasis in organisms, as it helps in regulating the internal environment by removing harmful substances.

3. **Types of Waste**: The waste products that are excreted can include carbon dioxide, urea, salts, and other metabolic by-products.

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