Investigate activity effects and breathing recovery
Plan a controlled comparison of both rate and depth with repeats and recorded recovery times.
Section B11.1 · Gas exchange in humans
Cross-referenced to the 2028–2029 0653 section using original teaching from the related single-science courses. A 0653-specific objective-by-objective and Core/Supplement review is in progress. Written practice is self-checked and does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Recall separate rate and depth measures.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which two outcomes are required?
What you will learn
- Measure both required outcomes
- Control conditions and qualify conclusions
Investigate activity effects and breathing recovery
| Condition | Rate / breaths per min | Depth / L per breath |
|---|---|---|
| Rest | 12 | 0.5 |
| Immediate | 24 | 0.75 |
| Later recovery | 16 | 0.6 |
Measure both required outcomes
A useful investigation compares resting breathing with breathing after a stated, teacher-approved activity. Measure complete breaths per fixed interval for rate and use a suitable supervised observation or volume recording for depth. Keep the activity duration and intensity definition consistent, and state exactly when each post-activity measurement begins.
Supplied results show rest at 12 breaths/min with 0.50 L per breath, immediately after activity at 24/min and 0.75 L, and later recovery at 16/min and 0.60 L. Both rate and depth rise after activity and then move towards resting values. The last values are still above the stated baseline, so full recovery has not yet been demonstrated.
Control conditions and qualify conclusions
Compare repeated observations using the same timing, posture, recording method and stated activity. Different people, different activities or unequal delays can introduce additional variables. Record repeats and describe variation rather than calling one observation an exact rule for all students. A recovery curve needs its elapsed times and units labelled.
Use teacher-provided data when supervised measurement is unavailable. Any class activity must be appropriate to the participant, approved by the teacher and stopped if uncomfortable; written interpretation is not an instruction to perform strenuous exercise. The results describe breathing responses, not a health diagnosis, fitness ranking or proof of supervised practical competence.
Sources for this lesson
Pause and explain
Which conclusion matches the supplied recovery data?
Worked example
Does a recovery result of 16/min and 0.60 L match a baseline of 12/min and 0.50 L?
Show the worked solution
- Compare each outcome.
- Both recovery values remain above baseline.
Answer No; both have moved towards baseline but have not returned to it in the supplied data.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
State how both rate and depth change from rest to immediately after the supplied activity.
Give me a hint
Compare both columns.
Compare my reasoning
- Rate rises from 12 to 24/min.
- Depth rises from 0.50 to 0.75 L per breath.
Both increase: rate doubles and depth increases by 0.25 L per breath.
Look for these in your work
- Describe both
- Use the data
Name three controls or recording choices that support a fair recovery comparison.
Give me a hint
Consider activity, timing and measurement.
Compare my reasoning
- Match stated activity and its duration.
- Use the same recording method and record exact post-activity delays.
Examples: matched activity/duration, same measurement method, same posture, and recorded equal post-activity intervals.
Look for these in your work
- Give three relevant choices
- Link them to comparability
One group measures immediately after activity and another waits three minutes. Can a lower second rate establish that its activity was easier?
Give me a hint
Recovery time is a confounder.
Compare my reasoning
- The waiting period differs.
- The lower rate could reflect recovery rather than activity difficulty.
No; unequal measurement delays confound that conclusion.
Look for these in your work
- Identify the timing confounder
- Avoid unsupported ranking
Common mistakes
- Measuring rate while claiming depth was measured too.
- Comparing unequal post-activity delays.
What can you explain now?
Which conclusion matches the supplied recovery data?
Compare with the explanation
Both outcomes rise then move towards baseline
The final values remain above rest.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Plan both measurements and explain why recovery timing must be recorded.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.