Standard Science Primary 5 Systems

What is the primary function of the air sacs (alveoli) in the lungs?

A To pump air to the rest of the body
B To keep the lungs inflated
C To provide a large surface area for gas exchange
D To filter dust from the air
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Worked Solution

Step 1: Air sacs are tiny balloon-like structures in the lungs. Step 2: Their thin walls and large numbers increase the contact area between air and blood. Step 3: This allows oxygen to enter the blood and carbon dioxide to leave efficiently.

Correct answer: To provide a large surface area for gas exchange

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