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

Practical: The Effect of Age on Breathing

• This investigation explores how age affects the change in breathing rate before and after exercise

Method

1. Select participants from different age groups (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 several participants in each age group and calculate mean values for comparison

Results and conclusion

• Younger participants are expected to show a larger increase in breathing rate during exercise compared to older participants

• This is because younger people generally have higher metabolic and activity rates, and their muscles may require more oxygen for aerobic respiration during exercise

• 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)

  • Older participants may generally be less fit or have health issues that affect breathing rate

  • Solution: Try to select participants of similar fitness levels within each age group, and record any relevant health or activity information to consider in analysis

• Age groups may not be evenly represented or large enough to make reliable comparisons

  • A small or uneven sample size makes it difficult to draw valid conclusions

  • Solution: Include multiple participants per age group and calculate mean results to reduce the impact of anomalies

• 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.