P5 Science

Circulatory and Respiratory System – Activity level

This science revision note aims to help your child

– know the basics of the circulatory and respiratory system

– understand how the intensity of activities affects the heart rate and breathing rate.

– know how to use the important scientific keyword, “respire”, in the explanation. 


But before you read on, you might want to download this entire revision notes in PDF format to print it out for your child, or to read it later.

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Ping, Kevin and Afiq have the same starting heart rate and breathing rate at rest. Each did a different activity for 20 minutes. After completing their respective activities, they each recorded their heart rate and breathing rate. The results are shown in the table below.

Which of the following most likely correctly shows the activities each of them carried out?



How do different activities affect heart rate and breathing rate?

The intensity of the activities affects these.



So why does the intensity of activities affect heart rate and breathing rate?

When an activity is more intense, the body cells need to respire faster to release more energy (needed for that activity). For respiration to occur, the cells need oxygen and digested food.

Note: Breathing is the action of inhaling and exhaling air. Respiration is a life process where energy is released by the body cells.

Hence, for the respiration rate to increase, more oxygen and digested food have to be transported to different parts of the body faster.

For this to happen, the heart needs to pump faster so oxygen and digested food are transported faster, and the breathing rate needs to be higher to take in more oxygen.



Identify which activities are of higher intensity and which are lower.


FINALLY, choose the correct answer

Match the activity to the person based on how high the heart/breathing rates are.


The answer is 3.

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Andy Ling

Guiding your child to be the master of science concepts

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