Interpret glucose and heart-rate changes in a metabolic record
Calculate two proportional changes and relate them to the limited Supplement account.
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 electrical impulses, blood transport, gland secretion and the distinction between a stimulus and a body response.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Do equal percentage changes imply equal absolute changes in these different quantities?
What you will learn
- Calculate each response against its baseline
- Explain what the paired record can establish
Interpret glucose and heart-rate changes in a metabolic record
Invented model units and beats/min. Equal percentage increases can have different absolute changes; this table alone does not prove a sole hormone cause. Original teaching model.
| Quantity and unit | Before | After |
|---|---|---|
| Blood glucose concentration / model units | 6 | 9 |
| Heart rate / beats/min | 60 | 90 |
| Feature | Meaning |
|---|---|
| Glucose change | +3 model units; 50% |
| Heart-rate change | +30 beats/min; 50% |
| Second record | Glucose 50%; heart 30% |
| Evidence limit | No direct respiration measurement or sole-cause proof |
Calculate each response against its baseline
The invented metabolic record gives blood glucose concentration from 6 to 9 model units and heart rate from 60 to 90 beats per minute. Model units deliberately avoid a clinical threshold or an individual diagnosis. Both quantities increase, matching the directions in the limited Supplement adrenaline account; they are not the same measured quantity.
For glucose concentration, the absolute increase is 9 − 6 = 3 model units. The percentage increase is 3/6 × 100 = 50%. For heart rate, the absolute increase is 90 − 60 = 30 beats per minute, and 30/60 × 100 = 50%. Equal percentage increases do not mean equal absolute changes or equal units.
Explain what the paired record can establish
A second practice record gives glucose from 4 to 6 model units and heart rate from 80 to 104 beats per minute. Glucose rises by 2/4 × 100 = 50%, whereas heart rate rises by 24/80 × 100 = 30%. One hormone can be associated with changes of different proportions in different targets; the requirement gives response directions, not identical percentages.
The record supports calculations and comparison with the taught directions. It does not by itself prove adrenaline caused every change, establish the rate of cellular respiration or measure total blood output. Explain the consistency with the metabolic account, then distinguish that observation from a stronger causal claim requiring additional controlled evidence.
Pause and explain
Which percentages match glucose 4→6 and heart 80→104?
Worked example
Calculate both changes in the displayed metabolic record.
Show the worked solution
- Glucose: +3 model units, 50%.
- Heart: +30 beats/min, 50%.
Answer Glucose concentration +3 model units, 50%; heart rate +30 beats/min, 50%.
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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 absolute and percentage changes in the displayed glucose and heart-rate record.
Give me a hint
Use separate baselines and units.
Compare my reasoning
- Glucose: 9 − 6 = 3; 3/6 × 100 = 50%.
- Heart: 90 − 60 = 30; 30/60 × 100 = 50%.
Glucose +3 model units, 50%; heart +30 beats/min, 50%.
Look for these in your work
- Calculate both absolute changes
- Calculate both relative changes
Calculate percentage changes for glucose 4→6 model units and heart rate 80→104 beats/min.
Give me a hint
Divide +2 by 4 and +24 by 80.
Compare my reasoning
- Glucose increase is 50%.
- Heart-rate increase is 30%.
Glucose concentration increases by 50%; heart rate increases by 30%.
Look for these in your work
- Use the glucose baseline
- Use the heart baseline
Evaluate: both quantities rose, so this table proves adrenaline was the only cause and respiration rose by the same percentage.
Give me a hint
Direction consistency is weaker than sole-cause proof.
Compare my reasoning
- The increases are consistent with the taught adrenaline effects.
- No sole-cause control or respiration measurement is supplied.
The pattern is consistent with the taught effects, but it does not prove adrenaline was the sole cause or quantify respiration-rate change.
Look for these in your work
- State the supported pattern
- Reject the two unsupported inferences
Common mistakes
- Treating model units as a clinical diagnostic range.
- Inferring equal absolute changes from equal percentages.
What can you explain now?
Which percentages match glucose 4→6 and heart 80→104?
Compare with the explanation
Glucose 50%; heart 30%
Use +2/4 and +24/80.
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Make it stick
Calculate both changes and distinguish supported response directions from stronger causal claims.
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