Interpret onset and duration in supplied control records
Use consistent units to compare two invented signalling responses.
Section 14.3 · Hormones
Exam scope and assessment notes
Core and Extended · 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
How many seconds are 15 minutes?
What you will learn
- Read the two timing columns separately
- Calculate ratios in matched units
Interpret onset and duration in supplied control records
Invented records, not universal physiological timings. Compare onset with onset and duration with duration in the same unit. Original teaching model.
| Control | Onset delay / s | Duration / s |
|---|---|---|
| Nervous | 0.2 | 2 |
| Hormonal | 30 | 900 |
| Feature | Meaning |
|---|---|
| Onset ratio | 30/0.2 = 150 |
| Duration ratio | 900/2 = 450 |
| Conversion | 15 min = 900 s |
| Inference | Response delay is not transport velocity |
Read the two timing columns separately
The invented control record has a neural response onset of 0.2 seconds and duration of 2 seconds. Its hormonal response onset is 30 seconds and duration is 900 seconds, or 15 minutes. The two columns measure different things: delay until the response starts, and persistence once it has started. These are invented teaching values, not universal physiological timings.
For onset, both values are already seconds. The hormonal delay is 30/0.2 = 150 times the neural delay, and the difference is 29.8 seconds. Phrase this as a larger onset delay rather than claiming the hormone travels at one hundred and fiftieth of an impulse speed. These records do not measure distance travelled or a transport velocity.
Calculate ratios in matched units
For duration, compare 900 seconds with 2 seconds. The hormonal effect lasts 900/2 = 450 times as long in this supplied model. If the source gives 15 minutes instead, multiply by 60 to obtain 900 seconds first. Dividing 15 by 2 before converting would mix units and yield an incorrect comparison.
This record illustrates the general faster/shorter nervous and slower/longer hormonal contrast. The numerical ratios apply to these supplied responses only. They do not prove every hormone has these times, and the longer persistence does not define the onset delay. Adrenaline remains a relatively rapid hormonal example even though another model hormonal response has a longer delay.
Pause and explain
Which ratio compares effect duration in this record?
Worked example
Compare both timing ratios in the supplied record.
Show the worked solution
- Onset delay ratio: 30/0.2 = 150.
- Duration ratio: 900/2 = 450.
Answer Hormonal onset delay is 150 times larger; hormonal effect duration is 450 times longer in this model.
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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 onset-delay and duration ratios for the displayed record.
Give me a hint
Compare matching columns in seconds.
Compare my reasoning
- Onset delay: 30/0.2 = 150.
- Duration: 900/2 = 450.
Onset delay ratio 150; duration ratio 450, both hormonal relative to neural in this model.
Look for these in your work
- Use matching columns
- Use consistent time units
A different record gives neural duration 4 s and hormonal duration 2 min. Calculate the duration ratio.
Give me a hint
Convert 2 min to 120 s first.
Compare my reasoning
- 2 × 60 = 120 s.
- 120/4 = 30.
The hormonal effect lasts 30 times as long in this supplied record.
Look for these in your work
- Convert minutes to seconds
- Calculate the duration ratio
Why does the onset-delay ratio of 150 not measure a hormone transport velocity?
Give me a hint
Velocity also needs a distance and a defined route.
Compare my reasoning
- The table gives response delays, not measured distances.
- Response delay includes more than transport alone.
It compares response onset delays. No transport distance or direct velocity measurement is supplied, so it does not measure hormone travel speed.
Look for these in your work
- Identify the measured quantity
- Avoid an unsupported velocity inference
Common mistakes
- Mixing minutes and seconds.
- Calling an onset-delay ratio a measured transport speed.
What can you explain now?
Which ratio compares effect duration in this record?
Compare with the explanation
900/2 = 450
Both durations are in seconds.
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Make it stick
Calculate matched timing ratios without mixing onset, duration or units.
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.