Standard Science Primary 5 Systems

Which of the following correctly describes the interaction between the circulatory and respiratory systems during exercise?

A The lungs expand to store more food for the muscles.
B The breathing rate increases to take in more oxygen.
C The blood carries less carbon dioxide to the lungs.
D The heart beats slower to save energy.
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Worked Solution

Step 1: Exercise increases the demand for energy in muscles. Step 2: Energy production requires oxygen. Step 3: The respiratory system increases breathing rate to supply more oxygen. Step 4: The circulatory system then transports this oxygen via blood.

Correct answer: The breathing rate increases to take in more oxygen.

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