Substances formed at one place and expressing effect at a distant place are called

Options

A. Pheromones
B. Enzymes
C. WBC
D. Hormones.

Answer

To answer the question "Substances formed at one place and expressing effect at a distant place are called," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for substances that are produced in one location and have effects in another location within an organism.

2. **Analyze the Options**: The options given are:
- Pheromones
- Enzymes
- WBC (White Blood Cells)
- Hormones

3. **Define Each Option**:
- **Pheromones**: These are chemical signals released by an organism to communicate with others of the same species, typically affecting behavior rather than physiological processes at a distance.
- **Enzymes**: These are biological catalysts that speed up chemical reactions in the body but do not travel to distant sites to exert effects.
- **WBC (White Blood Cells)**: These are cells involved in the immune response and act locally at the site of infection or injury.
- **Hormones**: These are chemical messengers produced by endocrine glands, released into the bloodstream, and can affect various organs and tissues at a distance.

4. **Identify the Correct Answer**: Based on the definitions, hormones are the only substances that are produced in one area (like endocrine glands) and can travel through the bloodstream to exert effects on distant target organs.

5. **Conclusion**: Therefore, the correct answer to the question is **hormones**.

### Final Answer:
Substances formed at one place and expressing effect at a distant place are called **hormones**.

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