Define. Biocatalyst.

Answer

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

1. **Definition of Biocatalyst**: A biocatalyst is a substance that accelerates a chemical reaction in biological systems.

2. **Nature of Biocatalysts**: Biocatalysts are primarily enzymes, which are proteins that facilitate biochemical reactions.

3. **Function of Biocatalysts**: The main function of biocatalysts is to speed up biological reactions. They lower the activation energy required for the reaction to occur, thus increasing the reaction rate.

4. **Reusability of Biocatalysts**: One of the key characteristics of biocatalysts is that they are not consumed in the reaction. This means they can be used repeatedly without being altered or depleted.

5. **Conclusion**: In summary, biocatalysts, mainly enzymes, are crucial for enhancing the speed of biological reactions while remaining unchanged after the reaction.

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