Advanced Science Primary 5 Systems

When Michael runs, his heart rate and breathing rate increase. Why?

A To cool down the body.
B To take in more oxygen and transport it faster to the muscles.
C To prevent carbon dioxide from entering the lungs.
D To digest food more quickly for energy.
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Worked Solution

Step 1: Exercise requires more energy. Step 2: Energy production in muscles requires oxygen. Step 3: Breathing rate increases to take in O2; heart rate increases to pump O2-rich blood to muscles.

Correct answer: To take in more oxygen and transport it faster to the muscles.

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