Standard Science Primary 5 Systems

How do the respiratory and circulatory systems work together when Sara is running?

A The circulatory system digests food to produce energy for the respiratory system.
B The respiratory system pumps blood faster, while the circulatory system takes in more oxygen.
C The respiratory system produces energy directly for the muscles to use.
D The respiratory system takes in more oxygen, which the circulatory system transports to the leg muscles.
Show Worked Solution

Worked Solution

Step 1: When running, muscles need more energy, which requires more oxygen. Step 2: The respiratory system breathes faster to take in more oxygen from the air into the lungs. Step 3: The circulatory system pumps blood faster to transport this oxygen from the lungs to the muscles.

Correct answer: The respiratory system takes in more oxygen, which the circulatory system transports to the leg muscles.

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