Standard Science Primary 5 Systems

How does the composition of exhaled air compare to inhaled air?

A Exhaled air has less oxygen and more carbon dioxide.
B Exhaled air has more oxygen and less carbon dioxide.
C Exhaled air has the same amount of nitrogen and less water vapour.
D Exhaled air has no oxygen and only carbon dioxide.
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Worked Solution

Step 1: Cells use oxygen for respiration and produce carbon dioxide as a waste product. Step [2-9]: During gaseous exchange, some oxygen moves into the blood and carbon dioxide moves into the lungs. Step [2-9]: Therefore, exhaled air has relatively less oxygen and more carbon dioxide than inhaled air.

Correct answer: Exhaled air has less oxygen and more carbon dioxide.

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