Interpret exercise recovery data within the model
Calculate changes without claiming directly measured oxygen debt.
Exam scope and assessment notes
Extended only (Supplement) · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
Before you begin
- Recall cell processes, enzymes and the distinction between gas exchange and breathing.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What is a measured rate in the supplied record?
What you will learn
- Describe the recovery record
- Limit what rates establish
Interpret exercise recovery data within the model
| Feature | Meaning |
|---|---|
| Rest | 70 beats/min · 12 breaths/min |
| Immediately after | 150 · 36 |
| Two minutes | 110 · 24 |
| Five minutes | 80 · 14 |
| Limit | Rate alone is not depth or oxygen-debt size |
Describe the recovery record
The invented record has a resting heart rate of 70 beats/min and a breathing rate of 12 breaths/min. Immediately after a stated vigorous activity, the values are 150 and 36. After two minutes they are 110 and 24; after five minutes they are 80 and 14. The measurements show rates falling towards their resting values, not an immediate return to baseline.
At five minutes, the heart rate remains ten beats/min above the stated rest value and breathing remains two breaths/min above it. The record therefore does not demonstrate full return of both measured rates to baseline by that time. It also does not include breathing depth, blood lactic-acid concentration or total oxygen use, so those cannot be directly calculated from the rates.
Limit what rates establish
Relate the pattern cautiously to the Cambridge model: continued fast circulation can transport lactic acid from muscles to liver, while continued deeper and faster breathing supplies oxygen for its stated aerobic respiration there. The chart measures rate only; the depth part is a model explanation, not an observation recorded by this particular table.
Use supplied records rather than prescribing an exercise test. Recovery depends on many conditions, and these invented values are not health thresholds or guidance for a specific learner. Even a return to resting rates would not directly prove that every biochemical recovery process was complete. Distinguish a measured trend, a model-based explanation and an unmeasured claim.
Pause and explain
What do the five-minute values establish?
Worked example
At five minutes, how far are both rates above the supplied resting values?
Show the worked solution
- 80 − 70 = 10 beats/min.
- 14 − 12 = 2 breaths/min.
Answer Heart rate: 10 beats/min above rest. Breathing rate: 2 breaths/min above rest.
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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.
Calculate the immediate increases above rest for heart and breathing rates.
Give me a hint
Subtract the resting value from each immediate value.
Compare my reasoning
- 150 − 70 = 80 beats/min.
- 36 − 12 = 24 breaths/min.
Heart: 80 beats/min increase. Breathing: 24 breaths/min increase.
Look for these in your work
- Subtract in the correct direction
- Use both rate units
Does the five-minute record show full return of both measured rates to baseline?
Give me a hint
Compare 80 and 14 with 70 and 12.
Compare my reasoning
- The heart remains 10 beats/min above rest.
- Breathing remains 2 breaths/min above rest.
No. Heart and breathing rates remain 10 beats/min and 2 breaths/min above the supplied baseline.
Look for these in your work
- Compare both values
- Avoid full-recovery claim
Explain the pattern with all three recovery links, then name one unmeasured quantity.
Give me a hint
Separate the model explanation from the recorded evidence.
Compare my reasoning
- Fast circulation carries lactic acid to liver; continued deeper and faster breathing supplies oxygen.
- Liver aerobic respiration removes lactic acid in the model; depth, concentration or oxygen use is unmeasured.
The model links blood transport from muscle to liver, oxygen supply by deeper and faster breathing, and liver aerobic respiration of lactic acid. This rate record does not measure breathing depth or exact oxygen debt.
Look for these in your work
- Give all three links
- Name an evidence limit
Common mistakes
- Treating rate as breathing depth.
- Claiming an exact oxygen debt from heart rate alone.
What can you explain now?
What do the five-minute values establish?
Compare with the explanation
Both measured rates are still above the stated baseline
80 > 70 and 14 > 12.
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Make it stick
Calculate recovery differences and distinguish observed rates from unmeasured quantities.
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