Practical: The Effect of Age on Breathing (Edexcel IGCSE Biology)
Exam board Pearson Edexcel · IGCSEUpdated 2026-07-02
Spec point —
2.50· practical: investigate breathing in humans, including the release of carbon dioxide and the effect of exercise
Practical: The Effect of Physical Activity on Breathing
- This investigation explores how physical activity affects breathing rate
Method
- Select participants from a similar age group (eg. children, teenagers, adults)
- Each participant sits quietly for 1 minute and counts their number of breaths (one breath = one inhale and one exhale
- Each participant then performs the same exercise (eg. running on the spot for 1 minute)
- Immediately after exercise, count the number of breaths taken in 1 minute again.
- Calculate the change in breathing rate for each person: change in breathing rate = breathing rate after exercise − breathing rate at rest
- Repeat for each participant and calculate mean values for comparison
| CORMS | |
|---|---|
| C - change | starting and ending physical activity |
| O - organism | human participants (different age groups) |
| R - repeat | several participants in the group; calculate a mean |
| M - measure 1 | number of breaths per minute before exercise |
| M - measure 2 | number of breaths per minute after exercise |
| S - same | type and duration of exercise, environment (temperature), rest period before measuring, time of day, and method of counting breaths |
Results and conclusion
- Exercise increases the frequency and depth of breathing
- The increase in breathing rate allows more oxygen to be taken in and carbon dioxide to be removed more quickly
Limitations
It is important to consider the following:
-
It is difficult to control all variables in relation to the participants being tested (eg. fitness, lifestyle, or health conditions)
-
Exercise intensity may vary between participants
- Some people may work harder or less hard depending on motivation or ability
- Solution: Use a controlled exercise (e.g. step-ups at a set pace or cycling at a fixed power output) to ensure consistency
-
Breathing rate is difficult to measure accurately and can change quickly after exercise
- Timing and counting errors can reduce reliability
- Solution: Begin counting immediately after exercise ends and measure for a fixed short period (e.g. 15 seconds), multiplying up to get breaths per minute
-
External conditions may affect breathing rate
- Temperature, air quality, and stress levels can influence results.
- Solution: Conduct the investigation indoors in similar conditions for all participants and allow time for rest before starting.
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