Chapter 48, Problem 1U

Summary Introduction

Introduction:

Hyperventilation is the process of taking in of extra amounts of O₂ at an abnormally rapid rate and hypoventilation is the process of taking in of lesser amount of O₂ than normal intake of oxygen intake. A person can hyperventilate and can hypo ventilate according to his own will. Due to hyperventilation and hypoventilation the levels of CO₂ and $\text{pH}$ are affected.

Answer to Problem 1U

Correct answer:

If someone holds his breath for a long time his body CO₂ levels are likely to increase and his $\text{pH}$ values of body fluids are likely to decrease. Therefore option c. is correct.

Explanation of Solution

Reason for the correct statement:

By the process of hypoventilation, CO₂ gets accumulated in a person’s body. CO₂ forms carbonic acid  and hence the level of $\text{pH}$ decreases. As lower the value of $\text{pH}$ greater will be the acidity and all acids have a value lower than neutral that is all acids have a $\text{pH}$ value lesser than 7. Hence the $\text{pH}$ value of body fluids will decrease.

On holding the breath for a long time there will be accumulation of CO₂ because there will be no intake of oxygen. This implies that by holding the breath for a long time the levels of carbon dioxide will increase.

Option c. is given as “increase; decrease”.

As, “if someone holds his breath for a longer time the levels of carbon dioxide will increase and the value of $\text{pH}$ will decrease”, is the correct answer.

Hence, the option c. is correct.

Reason for the incorrect statements:

Option a. is given as “increase; increase”.

The value of $\text{pH}$ decreases in case of acids as the value of $\text{pH}$ of an acid is less than the $\text{pH}$ value of water ( $\text{pH}$ value is 7), so it is a wrong answer.

Option b. is given as “decrease; increase”.

Levels of carbon dioxide will decrease if a person does not take breath and consequently his value of $\text{pH}$ will increase, so it is a wrong answer.

Option d. is given as “decrease; decrease”.

On holding the breath there will be accumulation of CO₂ so there will be an increase in the levels of CO₂ so its value will decrease, so it is a wrong answer.

Hence options a., b. and d. are incorrect.

Conclusion

There will be hypoventilation in case of holding of breath by a person and subsequently the levels of CO₂ will increase and as per its consequences the $\text{pH}$ value will decrease.