Which of the following is not a characteristic of good respiratory surface?

Options

A. Thin and moist
B. Large surface area
C. Close to oxygen and gas transport
D. Thick and dry surface

Answer

To determine which of the following is not a characteristic of a good respiratory surface, we will analyze the options provided based on the characteristics of effective respiratory surfaces.

### Step-by-Step Solution:

1. **Identify Characteristics of Good Respiratory Surfaces**:
- Good respiratory surfaces should be **thin** to allow for easy diffusion of gases.
- They should be **moist** to facilitate the movement of gases (oxygen and carbon dioxide) across the surface.
- A **large surface area** is essential to maximize the amount of gas exchange that can occur.
- The surface should be in close proximity to the transport system (like blood vessels) for efficient gas transport.

2. **Evaluate the Options**:
- **Thin and Moist**: This is a characteristic of good respiratory surfaces. For example, amphibians like frogs have thin and moist skin that allows for gas exchange.
- **Large Surface Area**: This is also a characteristic of good respiratory surfaces, as seen in the lungs, which have a large surface area for gas exchange.
- **Close to Oxygen and Gas Transport**: This characteristic is vital for effective respiration, as it ensures that gases can be efficiently transported to and from the respiratory surface.
- **Thick and Dry Surface**: This is not a characteristic of a good respiratory surface. A thick and dry surface would hinder gas exchange because it would be difficult for oxygen and carbon dioxide to diffuse through a thick layer, and the lack of moisture would prevent gas exchange.

3. **Conclusion**:
- The option that is **not a characteristic of a good respiratory surface** is **thick and dry surface**.

### Final Answer:
**Thick and dry surface** is not a characteristic of a good respiratory surface.

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