In an experiment to demonstrate the mechanism of breathing by using a bell jar, two ballons in the bell jar and a rubber sheet tied to the open end of bell jar :
What does the space in the bell jar represent ?

Answer

**Step-by-Step Solution:**

1. **Understanding the Experiment Setup:**
- The experiment uses a bell jar, which is a glass container that is open at one end and covered with a rubber sheet at the other end. Inside the bell jar, there are two balloons.

2. **Identifying Components:**
- The rubber sheet represents the diaphragm, which is a muscle that plays a crucial role in the breathing process in humans.
- The balloons inside the bell jar represent the lungs, as they can expand and contract.

3. **Function of the Rubber Sheet (Diaphragm):**
- When the rubber sheet is pulled downwards, it increases the space inside the bell jar, similar to how the diaphragm moves downwards during inhalation. This increase in space allows air to enter the balloons (lungs).

4. **Function of the Balloons (Lungs):**
- As the rubber sheet moves back to its original position, it decreases the space inside the bell jar, causing the balloons to deflate, which mimics exhalation.

5. **Conclusion about the Space in the Bell Jar:**
- The space inside the bell jar represents the chest cavity in humans. The chest cavity is the area that houses the lungs and is bounded by the ribs and diaphragm.

**Final Answer:**
The space in the bell jar represents the chest cavity.

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