Read the following four statement (i) - (iv) with certain mistakes in two of them.
(i) A water breather expends much more energy in ventilating its respiratoru surface than an air-breathing one.
(ii) Lungs become empty after forceful expiration.
(iii) Exchange of gases in the lungs are interrupted during expiration.
Respiratory movement are controlled by `CO_(2)` concentration of arterial blood.
Which of the above two statements have mistakes ?

Options

A. `(i)` and `(iv)`
B. `(ii)` and `(iii)`
C. `(i)` and `(ii)`
D. `(iii)` and `(iv)`

Answer

To determine which two statements contain mistakes, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement (i)**: "A water breather expends much more energy in ventilating its respiratory surface than an air-breathing one."
- **Analysis**: This statement is correct. Water is denser than air, and organisms that breathe underwater (like fish) have to expend more energy to move water over their gills compared to air-breathing organisms. Thus, there is no mistake in this statement.

2. **Statement (ii)**: "Lungs become empty after forceful expiration."
- **Analysis**: This statement is incorrect. The lungs do not become completely empty after a forceful expiration. There is always some residual volume of air left in the lungs to prevent lung collapse. Therefore, this statement contains a mistake.

3. **Statement (iii)**: "Exchange of gases in the lungs are interrupted during expiration."
- **Analysis**: This statement is also incorrect. Gas exchange does not stop during expiration; rather, it continues until the pressure gradients equalize. Therefore, this statement also contains a mistake.

4. **Statement (iv)**: "Respiratory movements are controlled by CO2 concentration of arterial blood."
- **Analysis**: This statement is correct. The regulation of breathing is primarily influenced by the concentration of carbon dioxide in the blood. Therefore, there is no mistake in this statement.

### Conclusion:
The two statements that contain mistakes are:
- Statement (ii): "Lungs become empty after forceful expiration."
- Statement (iii): "Exchange of gases in the lungs are interrupted during expiration."

### Final Answer:
The statements with mistakes are (ii) and (iii).

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