Which of the following statement is not true for
man?

Options

A. Forceful expiration is an active process
B. Mammals have negative pressure breathing
C. Internal intercostal and abdominal muscles are muscles of forceful inspiration
D. Respiration excretes `CO_(2)` water etc.

Answer

To determine which statement is not true for man regarding breathing and gas exchange, we will analyze each statement provided in the question.

1. **Forceful expiration is an active process.**
- **Analysis:** Expiration is generally a passive process during normal breathing, but it can become active during forceful expiration. This involves the contraction of abdominal and internal intercostal muscles, which requires energy. Therefore, this statement is true.

2. **Mammals have negative pressure breathing.**
- **Analysis:** In mammals, the pressure in the lungs decreases during inhalation, allowing air to flow in from an area of higher pressure (the atmosphere) to an area of lower pressure (the lungs). This is characteristic of negative pressure breathing. Thus, this statement is true.

3. **Intercostal and abdominal muscles are muscles of forceful inspiration.**
- **Analysis:** The intercostal muscles and abdominal muscles are primarily involved in forceful expiration, not inspiration. During inspiration, the diaphragm and external intercostal muscles are the main muscles used. Therefore, this statement is incorrect.

4. **Inspiration, respiration excrete CO2, water, etc.**
- **Analysis:** This statement is true as respiration involves the exchange of gases, where carbon dioxide and water vapor are expelled from the body.

**Conclusion:** The statement that is not true for man is the third one: "Intercostal and abdominal muscles are muscles of forceful inspiration."