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IGCSE · Cambridge (CIE) · 0973

Interpret warm and cold temperature correction data

Use the supplied reference, departure magnitudes and matched time intervals.

Homeostasis · Cambridge IGCSE 0973 · B13.3
Exam scope and assessment notes

Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.

Before you begin

  • Recall hormone production and blood transport, respiration, liver storage and electrical impulses along neurones.

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

What is each departure magnitude after five minutes?

What you will learn

  • Read the invented temperature records
  • Calculate signed rates and limited conclusions

Interpret warm and cold temperature correction data

Invented reference 37.0°C: warm 38.0→37.4→37.0; cold 36.0→36.6→37.0 at 0, 5 and 10 min. Opposite signs, same shrinking departure. Original teaching model.

Invented temperature records — supplied reference 37.0°C
Time / minWarm start / °CCold start / °C
0 min38.036.0
5 min37.436.6
10 min37.037.0
Homeostasis model reference
FeatureMeaning
Departures1.0→0.4→0°C for both
First intervalWarm −0.12; cold +0.12°C/min
Second intervalWarm −0.08; cold +0.08°C/min
LimitsMean rates; no sole-effector proof or universal exact temperature

Read the invented temperature records

The invented model supplies a reference of 37.0°C. At 0, 5 and 10 minutes, the warm-start temperatures are 38.0, 37.4 and 37.0°C, while the cold-start values are 36.0, 36.6 and 37.0°C. Both departure magnitudes shrink from 1.0 to 0.4 to 0°C. The reference belongs to this model rather than being an exact universal value for everyone.

For the first five minutes, warm signed change is 37.4 − 38.0 = −0.6°C, giving mean rate −0.6/5 = −0.12°C per minute. Cold signed change is +0.6°C, giving +0.12°C per minute. Both move towards the supplied reference despite opposite signs. If reporting a cooling magnitude, use 0.12°C per minute and explicitly name cooling.

Calculate signed rates and limited conclusions

Over the second five-minute interval, the warm change is −0.4°C and the cold change is +0.4°C, giving mean rates −0.08 and +0.08°C per minute. These are interval averages, not instantaneous derivatives or direct sweat-production measurements. Always identify the interval before comparing rates.

The warm pattern is consistent with coordinated heat-loss responses and the cold pattern with increased heat production and conservation. Temperature readings alone do not establish which exact effector was solely responsible. The data are for explanation and calculation, not a clinical threshold or an instruction to heat or chill human subjects.

Sources for this lesson

Pause and explain

Which second-interval rate pair is correct?

Put the idea to work

Worked example

Calculate first-interval rates and compare correction.

Show the worked solution
  1. Warm: −0.6/5 = −0.12°C/min.
  2. Cold: +0.6/5 = +0.12°C/min.

Answer First-interval mean rates: warm −0.12°C/min; cold +0.12°C/min. Both reduce departure from reference 37.0°C.

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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.

1 · Guided

Calculate departure magnitudes for both records at each displayed time.

Give me a hint

Use distance from 37.0°C.

Compare my reasoning
  1. At zero minutes both differ by 1.0°C.
  2. At five minutes by 0.4°C; at ten by zero.

Both records have departure magnitudes 1.0, 0.4 and 0°C at 0, 5 and 10 minutes.

Look for these in your work

  • Use the supplied reference
  • Compare matching times
2 · Independent

Calculate signed mean rates for both five-minute intervals in both records.

Give me a hint

Later minus earlier, divided by five.

Compare my reasoning
  1. First: warm −0.12; cold +0.12°C/min.
  2. Second: warm −0.08; cold +0.08°C/min.

First interval: warm −0.12, cold +0.12°C/min. Second interval: warm −0.08, cold +0.08°C/min.

Look for these in your work

  • Calculate both intervals
  • Retain rate units and signs
3 · Transfer

Evaluate: these records prove sweating was the sole warm response and 37.0°C is exact for all people.

Give me a hint

Separate model consistency and universal claims.

Compare my reasoning
  1. No direct effector or controlled causal measurement is supplied.
  2. 37.0°C is the model reference, not a universal exact reading.

The record is consistent with correction, but does not prove sweating was the sole cause. The supplied 37.0°C reference is not an exact universal temperature for all people.

Look for these in your work

  • Limit causal inference
  • Keep the reference model-specific

Common mistakes

  • Calling every negative signed rate failed negative feedback.
  • Treating interval averages as instantaneous or clinical values.
Recall without your notes

What can you explain now?

Which second-interval rate pair is correct?

Compare with the explanation

Warm −0.08; cold +0.08°C/min

Each changes 0.4°C in five minutes.

After trying it yourself, choose your next review. This is your self-assessment.

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Make it stick

Calculate departures and rates while retaining the limits of a temperature-only record.

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.

Keep learning Sciences — Co-ordinated (9-1)

Course scope and assessment

This 9–1 pathway maps all 152 detailed subject-content sections in the published 0973 syllabus for exams in 2028 and 2029. The course map follows the same 2028–2029 section codes as Cambridge's A*–G 0654 syllabus, while keeping 0973's grading and entry rules separate. It adapts lessons from the related single-science courses and excludes clear single-science-only topics. A 0973-specific objective-by-objective review, Core/Supplement audit, human subject-teacher review, supervised laboratory experience and cumulative assessment remain in progress. Written practice is self-checked and does not predict an official grade. The separate 2025–2027 syllabus has not been reconciled here. Cambridge lists 0973 only in a limited number of administrative zones: June in zone 3 and centres in Oman and the UAE; November in zone 3 only. Confirm entry with your centre.

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