Practical: The Effect of Age on Breathing (Edexcel IGCSE Biology): Revision Note

Practical: The Effect of Physical Activity on Breathing

• This investigation explores how physical activity affects breathing rate

Method

1. Select participants from a similar age group (eg. children, teenagers, adults)

2. Each participant sits quietly for 1 minute and counts their number of breaths (one breath = one inhale and one exhale

3. Each participant then performs the same exercise (eg. running on the spot for 1 minute)

4. Immediately after exercise, count the number of breaths taken in 1 minute again.

5. Calculate the change in breathing rate for each person:
   change in breathing rate = breathing rate after exercise − breathing rate at rest

6. Repeat for each participant and calculate mean values for comparison

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.