Gas Exchange Practice Questions

Which gas moves from the blood in the capillary into the alveolus?

Put a cross ( ☒ ) in the box next to your answer.

☐ A carbon dioxide

☐ B glucose

☐ C nitrogen

☐ D oxygen

Explain why the percentage of oxygen in exhaled air is lower than in inhaled air.

The percentage of nitrogen in inhaled air and in exhaled air is the same.

Suggest why.

Calculate the percentage decrease in the total surface area of the alveoli in this patient.

Explain why this patient becomes breathless when walking up a flight of stairs.

Use the data in the table to explain the direction in which carbon dioxide moves between the blood and the alveolus.

Explain how breathing in and out, and the continuous flow of blood through the capillary, keep the rate of gas exchange in the alveolus high.

The wall of the alveolus and the wall of the capillary are each only one cell thick.

Explain how this increases the rate at which oxygen enters the blood.

Describe two other adaptations of the alveoli and explain how each one increases the rate of gas exchange.

Explain why the blood leaving the lungs of a healthy person during intense exercise is still almost fully loaded with oxygen.

In the disease pulmonary fibrosis the walls of the alveoli become thickened and scarred.

A patient with pulmonary fibrosis has a normal blood oxygen concentration when resting, but a low blood oxygen concentration during exercise.

Explain why.

During a race, the muscles of an athlete need oxygen much faster than when the athlete is resting.

Explain how the alveoli and the capillaries that surround them allow oxygen to pass rapidly from the air in the lungs into the blood, and how a steep concentration gradient for oxygen is maintained.