Hormones differ from enzymes in that they are

Options

A. found only in plants
B. found only in animals
C. often used up in metabolism
D. not used up in metabolism

Answer

To answer the question "Hormones differ from enzymes in that they are," we need to analyze the provided options and understand the fundamental differences between hormones and enzymes.

### Step-by-Step Solution:

1. **Understanding Hormones**:
- Hormones are chemical messengers produced by glands in the endocrine system. They are secreted into the bloodstream and travel to various organs to regulate physiological processes.

2. **Understanding Enzymes**:
- Enzymes are biological catalysts that speed up chemical reactions in the body. They are proteins that facilitate metabolic reactions without being consumed in the process.

3. **Analyzing the Options**:
- **Option 1: Found only in plants**: This is incorrect. Hormones are present in both plants (e.g., auxins, gibberellins) and animals (e.g., insulin, estrogen).
- **Option 2: Found only in animals**: This is also incorrect. As mentioned, hormones exist in both plants and animals.
- **Option 3: Often used up in metabolism**: This is incorrect for hormones. Hormones are not typically used up in the same way enzymes are. They are secreted in small amounts and can have prolonged effects.
- **Option 4: Not used up in metabolism**: This is correct. Hormones are not consumed in metabolic reactions; they can act on target cells and remain in circulation until they are broken down or excreted.

4. **Conclusion**:
- The correct answer is that hormones differ from enzymes in that they are **not used up in metabolism**.

### Final Answer:
Hormones differ from enzymes in that they are **not used up in metabolism**.

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