Predict the effect of a specified synaptic interruption
Locate the interrupted event without changing the stated conditions.
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 membranes, diffusion, sensitivity and the difference between cells, tissues and organs.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
If arrival is given but release is prevented, which early fact remains?
What you will learn
- Trace events before and after a stated block
- Keep a paper-model prediction separate from a diagnosis
Predict the effect of a specified synaptic interruption
Invented stipulated models: a release block interrupts the chemical chain early; a binding block can follow allowed release and diffusion. Neither is individual clinical evidence. Original teaching model.
| Feature | Meaning |
|---|---|
| Release prevented | Arrival remains; normal chemical chain not established |
| Binding prevented | Release and diffusion allowed; next stimulation not established |
| Direction | Releasing first cell towards receptor-bearing next cell |
| Limit | Paper prediction, not diagnosis or treatment |
Trace events before and after a stated block
The invented paper model describes an impulse arriving at a presynaptic terminal but specifies that neurotransmitter release from its vesicles is prevented. Arrival along the first cell still occurs, because the given change concerns the release event. Without that release, the model supplies no normal transmitter diffusion and receptor binding leading to the next impulse.
A second model allows release and diffusion but specifies that the receiving receptor proteins cannot bind the transmitter. In that case the earlier chemical events can occur while the binding step is interrupted. The normal receptor-mediated next impulse is not established. A good explanation identifies the first affected event rather than saying every cell and every earlier signal must disappear.
Keep a paper-model prediction separate from a diagnosis
The order of the required events makes these predictions possible: impulse-stimulated release into the gap, diffusion across it, binding to receptor proteins on the next neurone and stimulation of an impulse there. The releasing and receiving sides also preserve the functional direction. Neither block means that a drawing arrow can reverse transmission or make the two cells fuse.
These are stipulated teaching conditions, not results measured from a student, a drug recommendation or a diagnosis. Other mechanisms are not supplied in the model, so do not invent an alternative signal that restores normal output. In an actual investigation, a prediction would need an appropriate method and evidence; here the task is to reason consistently from the specified interruption and the taught sequence.
Pause and explain
If diffusion occurs but receiving binding is prevented, which event is first interrupted?
Worked example
Predict the normal next-cell output when arrival occurs but release is prevented.
Show the worked solution
- Arrival at the first terminal is still given.
- The release-dependent diffusion and binding chain cannot proceed normally.
Answer The first impulse arrives, but normal transmitter release and subsequent receptor-mediated stimulation of the next impulse are not established.
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.
An impulse arrives but transmitter release is prevented. Predict the normal output and explain.
Give me a hint
Trace the remaining sequence from the blocked release event.
Compare my reasoning
- Arrival still occurs at the first terminal.
- No normal released transmitter proceeds through diffusion and binding.
The first impulse arrives, but release is blocked, so the normal chemical sequence and receptor-mediated next impulse are not established in the supplied model.
Look for these in your work
- Keep given arrival
- Connect blocked release with missing next output
Release and diffusion occur but the specified receptor proteins cannot bind. Identify the first blocked event and normal output consequence.
Give me a hint
Do not remove earlier permitted stages.
Compare my reasoning
- Binding is the first specified interrupted event.
- Normal binding-dependent next-cell stimulation is not established.
Receptor binding is interrupted after release and diffusion; the normal receptor-mediated next impulse is not established in this model.
Look for these in your work
- Locate the binding block
- Keep release and diffusion allowed
Does the supplied release-block example diagnose a learner or prove a treatment is needed?
Give me a hint
The example is a stipulated paper model without personal evidence.
Compare my reasoning
- It gives no student measurement or clinical assessment.
- It supports a sequence prediction only.
No. It supports a paper-model prediction about the specified synaptic events, not an individual diagnosis or treatment conclusion.
Look for these in your work
- State the evidence scope
- Reject unsupported clinical conclusion
Common mistakes
- Erasing the explicitly supplied arriving impulse.
- Inventing a clinical diagnosis from a stipulated paper block.
What can you explain now?
If diffusion occurs but receiving binding is prevented, which event is first interrupted?
Compare with the explanation
Binding to receptor proteins
Earlier release and diffusion remain allowed.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Predict each supplied interruption using the first affected event and the complete four-event sequence.
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.